I have the sister ship to the SV 264.....the SV 263. The bumpers on these units (at least mine) has an extra "C" channel welded within the "I" bean at the bumper, firming up the bumper some. I carry the spare tire on my bumper, along with 2 battery boxes holding some chock blocks....that is the limit of what I feel safe with back there.
It looks like the luggage rack would actually be attached to the frame, not the bumper....that is good thing. The bad thing is that I don't think the frames on these trailers are true "I" beams. It looks to be 2 narrow flat bars welded to a wide flat bar. These frames are probably manufactured just strong enough to carry the wieght of the trailer, and no more......that keeps them light and the overall weight of the trailer down.
Once you start adding weight to the rear of the trailer, then have to add weight to the front to keep the tongue weight in range, I wonder if that is going to stress the frame too much.
IMHO, a small load back there might be OK, but definitely not a couple hundred pounds.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263