Another fun project.
Have pondered this exact same thing a couple times with an electric bike for touring. If only solar recharge feasable would be the greatest thing ever. Not an expert but my basic understanding is demand use exceeds slow solar recharge capacity. Damn. But going to campgrounds or other 110v source, can charge overnight. Ideal 2 batteries.
Having built many years ago a basic bike trailer from cedar and metal studs to do touring, didn't work out well for me and had to scrap the bike touring thing quickly.
Trailer was maybe 18x30 and light. Great.
Problem was my camping equipment and stuff was too heavy. Didn't have the luxury of ultralightweight gear back in the day.
Hard to pedal, never mind uphill and wind, plus braking hazard from momentum. Especially downhill. Just my experience fyi.
There is a traveler setup like this on YouTube who does this. Think it's corroplast if I remember correctly.
But back to the build.
What will you be doing for axle and wheels? Dimensions? Or did I miss that?
Bike racers measure everything in grams so whatever you can do to the extreme to reduce weight is huge.
Less paint and glue to minimize weight.
So why not a lighter floor than OSB? Would think this is the ideal place for a luaun foam sandwich torsion box that everyone talks about.
And in theory, just the torso or major weight bearing section. The ends could be even lighter, just luaun.
Couple thoughts to ponder.
On the road to Shambala...