Ok, so I put in the tongue extension/backbone (a la gchoe) today and yesterday. Grade 8 1/2" bolts (2 on the tongue, 1 on the rearmost crossmember) and grade 8 3/8" bolts in all the other crossmembers. Receiver on the back for bike racks just in case.
Only thing left to do is put the hitch itself on the front of the tongue. I'll be putting the base on pretty soon.
Question: how long do you all think I should make the tongue extension beyond the cabin itself. My cabin is 11 feet long. Relative to the 4'X8' trailer platform, the cabin will sit with 2 feet of overhang in the front and 1 foot in the back. If I leave all of the steel tube extending out front the total trailer length from tail to hitch will be 16', with 5' of tongue beyond the cabin. Is that too much? Should I cut it down a bit? If so, how much? I would like to put some kind of tongue box on as well as a flip-up jack.