As is so often the case, I'm concerned that any attempt to build something that looks nice, is functional, reliable, and lightweight would cost more than I could buy something used already made. Anything that is truly reliable, nice looking and functional is not cheap. And anything cheap, is not all of the above.
Dick, if you could fit your car into an eight foot trailer, it would be really hard to beat something like this:
http://cgi.ebay.com/ebaymotors/ws/eBayI ... gory=80770
If the link is dead above, it was a used 5 x 8 enclosed trailer with a side door and a back door. I think such an animal could be had for anywhere between $700 and $1500 locally, used. The more patient you are, the cheaper you can get one. I know because I almost bought one awhile back.
It's just really hard to imagine any solution that I created that would cost significantly less and be anywhere nearly as good. The only problem is that I don't want to be stuck with an enclosed trailer all the time. So.. maybe I have two trailers... a cheap open one, and a nicer enclosed one. Yeah, that would work. My wife would love that.
Miles