One thing that helped us when we looked at used TM's was the opening/closing checklist that we received from a kind board member. The dealer that was selling our TM didn't know how it was supposed to be opened and closed and if you don't do it right you can do some damage.
I believe that there is a opening/closing checklist posted here and also a manual. It would be helpful to print both of them out and read through them before you go to look at used TM's.
Our 2720 is a 1997, and did not have the rounded wheel wells. The rounded wheel wells help prevent damage in case of a blowout. If you buy one without rounded wheel wells I would plan on doing the modification that's described on the board. It doesn't cost much, just takes an afternoon. We had a blowout and were very glad that we had made the modification.
Here is the link to a manual for a 2720:
http://www.trailmanorowners.com/foru...ead.php?t=2472
Here is the link to some other checklists, including opening/closing:
http://www.trailmanorowners.com/foru...ead.php?t=2358
I have a brochure that describes the opening/closing procedure in detail, I could email it to you if you'd like.
If you have time it would be good to check out all the appliances to make sure they're working, especially the ones that are expensive to replace.
The interior lights in the very front of the trailer are controlled right at the lamp and also via a toggle switch located in one of the ceiling vents (surprise, we thought ours were broken) so keep that in mind if you can't get them to go on.
Hopefully others will chime in here. Good luck with your search!