Questions about design for ultralight bed-on-wheels (codename: Siesta)

[1000arms]

... I'm not sure if i can find marine grade plywood locally but i'll try. ...

... One thing I'm noticing is that with this width I'm just a little bit wider then a 4x8 sheet of plywood, any narrower and a double bed won't fit. right now I've just been intending to cut two sheets to 30" wide then mount them side by side with some extra support under the part that's not under the tongue to axle bar, but I'm wondering if I should be doing something different.

Some plywood is available in sheets larger than 4'x8'. Try searching for "5'x10' marine plywood" to get you started.

It is possible to "scarf" sheets of plywood together. Look at the following book cover (Using Amazon's "Look Inside"), for the thin diagonal line across the plies of the plywood sheets joined together, to see scarfed plywood:

 

[Betonhaus]

just temper any advice with a bit of skepticism. some builders are very knowledgeable, but there are also folks building flush, hollow core door floored, units covered with roofing tar and foam insulation boards held together with cable ties and aluminum hvac tape. and everything in between.

Hey if it works almost as well as a specialized solution but costs a fraction of the price...

 

[s.e.charles]

oh lord help us and save us . . . . .

 

[NatersXJ6]

Have you thought about building the wheels into the sides of the trailer instead of having outside fenders? It gives you more interior room and I think might be more aerodynamic, but a blowout is more likely to cause significant damage to the trailer.

 

[Betonhaus]

I don't see how it would add more interior space, but it would make getting in and out of the trailer easier by raising it up. I don't know if a narrower wheelbase and higher center of gravity would affect stability too much, and I'd have to have a more complicated setup underneath to bolt the axles on at the right height.

 

[Peter_n_Margaret]

No timber, no steel would be my start point.
Fibreglass sandwich panel glued together with Sikaflex 252 or similar and pultruded FRP A frame and suspension mounts. No "chassis" required.
Cheers,
Peter
OKA196 motorhome