I built an insert for rap-around seating then mounted Yakama truck bed mounts on the front of it so we can carry two bike on the inside of our 13 ft boler.

That's pretty slick. I've been wrestling with attaching a receiver hitch to the bumper so I can use the same hitch-mount bike rack I do when I'm not pulling the trailer. It's worked insofar as the bikes haven't fallen off, but the bike rack, the bumper and the frame all flex so much that I keep breaking the welds. So I keep putting more angle iron, steel and bolts back there to reinforce it. If I ever get it totally solid, I'll post pix up -- if I'm not too embarrassed with my Frankenstein fabrication.

We have a solution to that problem that might work for you .. works great for us. Jim made a brace that attaches to the band on the trailer and to the bike rack. There is no flex at all... the bikes stay still and don't move back and forth.

great idea, I will see if it will work on my Trillium. the receiver is coming by mail.
is the receiver welded or bolted in to the bumper? and have you reinforced the welds in any way?

thnx
Mo