Wow that sounds like a gruling road trip. I guess going light means sharing a lot of things. I love to ride but I like a few more creature comforts.
One little trick is to ship your clothes "ground" to your destination and return them similarly. It can be relatively cheap. Or the old backpacker's trick - wash one, wear one. You're only packing one at a time. REI sells light travel clothes that dry quickly and look decent.