having built on a tractor supply no-floor trailer much like this one and then having two tent trailers (PUP) given to me last year for nothing, just come pick them up, I would really recommend finding an old PUP on craigslist, ebay etc.
First of all, a PUP frame is normally 5' wide, IMO the perfect width for a TD, this will take away any headaches with how to support the overhang (you really don't need to anyway, the nose wall and galley wall are all the support the TD needs)
PUP frames are already built strong enough to stand on and still be light to tow, you will only be sleeping on it with your weight spread out by a mattress, put your floor on the frame and build away.
Most PUP's frames will also let you have a 10' length, with no axle moving worries, another plus in my book.
A PUP on craigslist in worn out, mouse infested condition should be free or nearly free, however it should come with plenty of usefull stuff, the one I tore down for a utility trailer netted me a collection of lights, a power center (110 to 12v), sink, faucet, ice box, fire extinguisher, door latch, draw latches, awning track, and some other stuff I can't think of right now. It also has a nice torsion axle. between the money all that stuff would cost even on Ebay, you could buy a nice utility trailer if you still want to and have money left over, but as I said before I will always be recommending just using a PUP frame from now on.
also forgot to mention the nice pile of scrap metal from the PUP teardown, a few more dollars in the pocket
