
Also I saw your comment on the OSB, and I now have pretty much decided to stop buying it. At the time, I had less money and more time than I do now. Now after using it for that and various shelves I've decided it's not worth the small savings over plywood, which I would use if I did this again.
...which may not be likely, given that (with the lack of time and all) we bought a cheap pop-up a few weeks back and the wife would like a hard sided camper at some future time. Buy a bigger vehicle and this is what happens (the opposite of the 25 MPG you got towing the teardrop!).
I'll be following this to see how it ends up!