I saw a great seatpost on a bike earlier this week. The rear rack was welded directly on the seat post....it was all one unit. The rack was built on the same type and diameter tube as the seat post. Seems it would be much better than the clamp-on racks.
I have biked once (single track) with my 8x10 and Reis pod...60 pounds of equipment. I would do it again, as long as there were no significant hills and it was the only way to get there fast enough if hiking in would take too long. But a trailer would be the way I would have to go if I were to do it regularly (or get a light weight 8x10 system).