Got the first project on my build (mostly) done today. Installed 3/4 " XPS insulation, 19/32" plywood underlayment, and then re-installed the factory wood floor on top of that. Right now everything is "dry fitted" and I still need to go get longer M8-1.25 bolts to attach everything to the factory tie down points and seal the plywood subfloor. It looks like I will probably also have to use a router on the plywood subfloor if I want to re-use the plastic covers that came with the factory D-Rings.
The first step was to take up the factory wood floor. Getting it started was a little nerve wracking attacking a brand new van with a pry bar and wood shims. Once the first row of glue "pooped", I just used 3 2x4's and worked my way from back to front until I got to the slider. From there, it just took one 2x4 to get the rest of the way done. All of the glue stayed on the metal and the underside of the floor held up reasonably well. (I didn't bother trying to take up the glue, since the insulation would sit on top of it.) It was a little complicated getting the factory floor out of the van and definitely a 2+ person job. It is a single sheet a little over 3/8" thick so not too heavy, but cumbersome to move around, with a fair degree of flex over the 12' span. The first picture of the factory floor before taking it up.
On of the advantages of the factory floor is that it is a perfect template for laying out the sections insulation and sub-floor, including location of the factory tie down points. Basically, we laid out the three sheets of plywood laterally on the driveway and put the XPS insulation on top of that, ripping one sheet of insulation into 2 - 2' wide pieces so the seams of the insulation and subfloor did not overlap. After that it was just a matter of laying the factory floor on top, tracing the outline and the factory tie down holes, and cutting with the jig saw. (Note, at that point I was so excited to start cutting that I forgot to take pictures of laying everything out. Hopefully the description will help people if they want to try and replicate what I did.) I have to say, trying to find 3/4" XPS in stock in our local stores was a challenge. Ultimately, I settled for the "green stuff", instead of the Owens Corning "pink stuff" I have seen most people use. It was fine working with it and appeared to withstand pressure reasonably well. The second picture shows the insulation down.
The last step was repeating the process for the plywood subfloor. A little harder cutting with the jig saw, but overall not a problem. The last picture shows the subfloor laid out (with my little helper (grandson) inspecting). My "helpers" had to go so I didn't get a chance to take a picture with the factory subfloor on top of the sandwich.
Overall, I am please with how everything worked out. Started with a plan and just took it one step at a time. Much thanks to those on the Forum who suggested purchasing and re-using the factory wood floor. The laminate is heavy duty and adds strength to the overall package. Since it is one piece, it minimizes that need for worrying about seams in the subfloor and the top plastic "coin" layer seems durable enough that (at least for now) I am not going to worry about putting vinyl or laminate on top of that. Having an accurate template made it a piece of cake cutting everything out.
Now to finish this and move on to setting up the fixed bed area. It feels gratifying to finally take the first step (of many!)