From what I learned on my '63 T-20, is that the frames are burly, but will flex.
On my first month in as a brand new travel trailer owner, I knew enough to know I needed to pull the wheels, replace the bearings and brake shoes. But I didnt know enough NOT to try and jack up the trailer by the tounge jack and 2 jacks on the rear bumper. It didnt dammage the frame, but it flexed enough to buckle the aluminum skin at both rear corners.
Leasons Learned: a) Don't do that. b)The frame is tough, but not entirely rigid.
I'd imagine on your trailer, with 2 more feet on either side of that single, itty bitty axle, there might be a little more spring in the rear.
If the jack stands are stopping the wiggle, and you don't see any signs of the skin buckling in the corners, then I'd think your OK.
Champagne wishes and Caviar dreams!