The answer is completely dependent upon the camera that will grace the tripod. If you shoot an older Korona you could easily use a Ries J100 and not have to many mobility issues. My 34# Wisner 12x20/8x20/11x14 Tech Field requires a Ries A100 that tips the scale at #13 just for the tripod. That is nearly a #50 camera/tripod combination. Aside from regular visits to the gym to lift weights you learn rather quickly to be highly selective where you drop legs. Gitzo produces a carbon fibre tripod that is interesting and very light weight.

Good Luck!