Randy, unless there's a point that I missed, I don't see what's "cobbled" about using F to RCA adaptors with the F type wall plates that you saw at HD. MonoPrice and others do have RCA wall plates, but I don't see where you should bother.
On the question about receivers with two sub outputs, most don't allow for separately calibrating the outputs for different sub level and distance. Even the few that do provide for separately calibrating the two outputs still are working with just the same .1 channel carrying the same source material, not a totally separate sub channel.
