Started on some fabrication today after picking up some material yesterday. I bought tongue & groove 3/4" ply for flooring, 3/4" birch veneer ply for the overhead bed (I'll make this a slide out), a piece of oak to face the slide out bed, some poplar for the slide out supports, and 125' of 1" 14ga steel tube (they didn't have 16 ga in stock, not a big deal). This is more tube than I need, but 1" is great to have on hand for random projects.
I got a litter further along than this, but this is the last picture I took. Sorry for the blur, my phone camera has intermittent focusing capabilities.
The frame looks convoluted but there's method to the madness. The double tubes going across are to support the plywood seam. The red circles show approximate bolt down locations for the front.
After lots of paint/sealer on the ply and paint on the steel, I'll be attaching ply to the bottom of the floor frame with large head self drilling/tapping screws. The space between the tubes will get 1" XPS insulation for an insulated floor. I'm not sure exactly what I'll do for the floor material to stand on; I'm leaning toward laminate flooring with a thin under lay of ply.
I should be able to finish up the steel tube frame tomorrow, hopefully get some paint on it & the plywood floor. I'll be busy part of Monday so that's a good time for paint to be drying.