[RockyMtnRay]

I personally wouldn't put any storage containers on the back of the TM. Any weight back there does two things: (1) it unweights the hitch and (2) adds to the behind-the-wheels moment arm. Both of these effects can easily lead to hard to control sway. There have been posts on this forum of people encountering sway even with a couple of relatively lightweight bikes mounted fairly closely to the TM's bumper.

One of the main reasons that TMs are inherently sway-resistant is their wheels are mounted much further aft of the trailer's center of gravity than are the wheels on other travel trailers. Even light weights at a long enough distance behind the TM's axle can exert a substantial leverage and drastically reduce that inherent stability.

I would suggest that instead you put a roof mounted carrier on your tow vehicle...and mount it as far forward as possible so that as much of the added weight as possible is over the front wheels of the tow vehicle.