Motorcycle on back of Travel Trailer

Looked at that too, and only for a 300 lb scooter, and didnt feel safe.
The TT makers that offer factory racks on the rear limit them to somewhere between 225 and 300 lbs because the leverage of that much weight, that far behind the axle is significant. Most wont cover anything off the rear beyond the spare tire without negating the warranty.

There are some doing it with 5ers, but they are much heavier units than the Crossroads tt's.

I agree with beemer - unless you have a unit specifically designed to handle such a load (which I don't think that probably is), loading that much weight on the rear is a rough idea. There are many who cringe at the notion of a simple bike rack mounted to the rear of a trailer - much less the 750+ pounds in bike and carrier weight you'd be considering. Between the frame damage and the load disparity, I don't expect it would end well.

I don't know what you are towing with, but if you have room and payload available, you'd be much better off getting it into the bed of a pickup.

to begin, the bumper is only strong enough to carry it's own weight, then taking 575 lbs off the tongue is in itself a dangerous practice

In general it is not a good idea. The TT is not designed to carry weight back there.

It will take weight off of the tongue which could drastically affect handling and will stress the TT frame carrying weight far back behind the axle.