RCA,
Glad you finally found one after many moons of looking. The grandsons and I went to a jet meet in Waco last week, guy said they had 53 planes on Thursday, but down to 47 when we got there. Other six perished during the event. First time I had seen them fly, but I have real-flight simulator here for kids to play on, and they have fun with the jets, and really enjoyed seeing the real thing. Now back to TM tips for what they are worth.
Check to see if your unit has a lift kit. You can tell by looking at the axle on each side where the trailer frame is attached. The lift kit is nothing more than a piece of square steel tube about 24" long that is bolted on top of the axle and raises the trailer about 2".
If you don't have a lift kit, think seriously about buying one from the factory or local supplier. They are cheap (about $35 I think) and will save your rear jacks from dragging on grades (like some driveways or service station entry ramps or campground hills) If you don't have a lift kit, I advise you to carry 2 pieces of good 1" x 6" x as long as will fit in your bumper box to use as ramps when you get to a spot that it won't go without dragging. Carry a couple of short pieces as well for supports when the ramp is several inches off the ground on more severe grade changes.
Whether you have a lift kit or not, be especially cautious about sudden grade changes. Proceed very slowly (with windows open and radio off so you can hear) and preferably with somebody outside watching to ensure clearance if possible. Stop immediately if you feel any change or lurch, or hear anything.
I also carry four wooden jack pads for the corners to save time and effort. Some campgrounds require them, and they are always nice to have.
Using a skill saw, I fabricated the base (from a 2" x 4" about 18'" long) into the shape of a paddle, then nailed a 8" piece of 4" x 4" onto the big end of the "paddle." They provide more stability at the corners, since the jacks extend less, are especially handy when one side or corner of the campsite is much lower than others. And all DW has to do is place them directly under each jack so the pointy end of the handle is directly under the pointy end of the corner jacks; they are then properly positioned for me when I come around with the drill to lower them. They dovetail nicely in the bumper box.
The drill? Oh, yeah, a heavy-duty cordless drill with a L-shaped steel rod about 8" long with a 1" bend at the end will make short work of extending/retracting the jacks. Keep the jacks washed down to remove road grime and spray them regularly with WD-40.
I also carry a leveling board that is about 30" long, 1" x 6" x 15" on one end and 2" x 6" x 15" on the other (screw another piece of 1" x 6" to one end). It also travels in the bumper box with a pair of rubber gloves for sewer work 4 plastic wheel chocks (cheap at Walmart) and a 90-degree sewer connector. Not much room in the bumper box for anything else, but everything I need for setup/takedown, unexpected grades or sewer work and dump station chores is stored back there where I can get to it without opening the trailer. We carry a squirt bottle of sterilizing gel in each front door pocket of the TV for use after all such events.
A small nylon (or other synthetic) tarp is also handy. We keep one in the exterior storage. Good to have if you need to crawl under or around the trailer or if it rains and you want a "porch" around the steps or under the outdoor shower.
The newer units have clips on the back of the sofa to carry the center awning support and extension rod. If your unit doesn't have them, you can buy them at the hardware store for a couple of dollars and attach them to a sofa back. Good place to keep them and easy to access.
Keep at least one spare electric cord adapter in your tool box (so only you know where it is when you need it) as well as a supply of fuses. Fuses know when the closest hardware store or service station/convenience store closes, and won't blow until 10 minutes later. Check the fuse in your Thetford; if it's a 5 amp, replace it with a 10. I've heard some dealers say (off the record or they could get in trouble) to just hot-wire the toilet motor, since the entire trailer operates on a 15-amp fuse anyway. I probably won't but it's interesting to think about.
Consider investing in a grease gun to take with you if you don't already have one. The trailer has easy-grease axle bearing hubs and the trailer ball needs a shot every few days. WDH hitches also work better if the lift arm attach points are greased. Mine rides in the TV.
If your unit already has levels attached (from previous owner) you will find they are handy. If not, you can spend as much or as little as you want. Some owners spend 20-30 bucks for the big inclinometer levels that they can see out the back window while the unit is still attached to the TV. Some dealers say to stick a round 2-dollar bubble-in-the middle unit onto the tongue. Some people just carry a small level in their TV and place it on the tongue when setting up. Your choice. Everybody agrees the fridge should be level, so you have to figure out how you want to level your unit.
Check your awning end-covers to be sure they are still sealed. If not, you can fill the rolled-up awning with water as you drive in the rain. And if you don't extend the awning to dry, the water can cause big-time discoloration, mildew, and other bad stuff. I advise you to extend your awning after every trip before you store the trailer, just to be sure it works properly and that the awning is dry. Use white silicone sealer on the awning end covers if necessary. Also check the end covers for integrity. The plastic on the older units (and maybe new ones as well) is prone to age-cracking, and small holes are not apparent until you look closely. Most RV dealers sell them. Also check roof seals, especially those around vents and air conditioners. Older units also have center strips that are more leak-prone, so check them carefully as well. One or two tubes of sealant will normally do an entire TM roof. Cheap insurance.
Be sure to note that the bed pin (that plugs into the bathroom wall when set up) is also the emergency exit. If that pin isn't inserted, the entire bed can unceremoniously tip whoever is on it onto the ground. Some funny stories on this site about that, but probably more important for people with kids who like to jump up on the bed (and I've never seen one that doesn't
Many of the older units have experienced some problems with the corner draw latches over time. The factory has replacement latches and wall anchors they recommend for replacing them. Prices are very reasonable.
Old-style shell latches are also problem-prone. Several good posts recently on that subject.
Good luck with the new unit. Have fun at the flying fields.