I found this set of pictures of a quad home built by Alex Reahin Russia. All four wheels are 26″, left rear wheel is powered by manpower and the right one has an engine. The machine can be disassembled and transported easily.Alex has more experience with building recumbent vehicles. I especially like his description of ther first recumbent trike he built. You can read a not too long article about where he saw a recumbent for the first time and about all the things he had to do in Russia to build such a nice trike.