do sonotubes hold up long though? Putting wet legs in and rain/snow possibly getting in the rear door? Not an often occurrence, but it does happen. The wear and tear is what I would worry about, my 3/4" ply is taking a beating on the outer edge.
Have to get the HD ones from a building supply house, not the Home Depot ones. 12" PVC is better.
This doesn't really fit with the original simple request but you may want to grab a few of the photos for ideas.
http://www.csmtransportequipment.com.au/surveyor
> 12" diameter sonotubes are light, and inexpensive. I use 4 of them in the back of a Trailblazer. PVC pipe is good too, but more costly.
I use 4 4.5'x10" PVC pipes as a base and then place a sheet of plywood on top. The pipes are secured by sandwiching them between 2 2x4s at each end using threaded rod. I then attach the 3/8 plywood deck to the 2x4s. I also attach a sheet of plywood to one end of the tubes to act as a stop keeping the tri-pods in the tubes and anything on the deck from sliding forward in the tube. I keep the gun and GPS up front and the other stuff in milk crates on the deck. While cheep and functional, it is still a little on the heavy side and I am considering going to an aluminium box in the future (but then I've been telling myself that for years now).