Hi Ed, hope you're a big guy since solo paddling a double in any kind of winds would be dicey. I don't see any insurmountable obstacles to achieving your goal of center and aft controlled pedals. A couple ways to go about this would be pedals in series with the aft ones but this would have a fair amount of friction, especially when operated in the middle. Any kind of adjustable linkage between the two footbraces would probably introduce lots of slop. Especially if the adjustment was made with 1"webbing. Your front pedals should probably be bungied so that they are pulled forward firmly to keep slack out of the system. Definately get a rudder. If this all gets too complicated you could probably just have a couple of long lines of 1/8" kevlar or spectra lines that could be connected to the rudder directly routed forward through lots of deck line loops then up to jam cleats on either side of your cocpit. crude? but effective.