The design went through one major revision and several minor changes (that's where the version 2.2F comes from). Ultimately I wound up with a 5'x 9-1/2' trailer on a 5' wide Northern trailer (thanks to someone who uploaded the trailer model, I have been known to steal stuff, or 'borrow' extensively). The primary material is 1-1/2 foam. I started with 2" foam, but after thinking too long about how to dress out 1-1/2" wood stringers (2x4 nominal lumber actually measures much closer to 1-1/2" x 3-1/2" and other 2x widths are similarly sized), switched to the 1-1/2.
I started with a 4x8 trailer, but reading all the comments on this board about sizes, and "nobody that built a 5 wide ever wished they had done a 4 wide" convinced me to go with the 5 foot width. I like the foamy concept, both from the cost standpoint, but because of the weight possibility's. I also tend to prefer straight lines. I thought it would be much easier (and faster) to build angles, i.e. a "weekender" profile, rather than going through all the work I've seen others spend to do a nice curved, "traditional teardrop" profile. Over many years, I learned long ago, that unless I am careful, that I can spend forever building something then never get to using it. At least, for me, the primary purpose of building this would to be done and using it.
I'm posting the actual sketchup file so feel free to download it, use it, modify it, I'm not in this professionally so have fun with it if you want. I built this in Sketchup 17 so you'll need to use that version or newer. Unless there are significant changes (functions that make life much easier) this is probably the version I'll continue to use. I chased AutoCAD versions from 2.50 up through 14 and newer, some changes I loved, others not so much. I'll only do that when really neccessary now.
A couple of quick tips in building with sketchup. Turn everything you build into a group. That's probably the basic block in the program. Group these groups into larger assemblies. I keep the Outliner open full time and rename the groups to make sense out of my builds. Some groups I'll make into components so I can open doors, lids, etc. Use the interact tool to activate these. Along with the original 5x9 trailer, I've also downloaded appliances and modified them to give myself a sense of what I'm building will look like.
Hope you enjoy the file. I'll answer questions on it, or my use of sketchup if needed. I also may make more comments about this build later.