If the Privia is just a 'dumb' MIDI controller for the T2, can't you place them so close together that the T2 sits on top of the Privia and obscures all it's controls (apparently, you don't need them) and gets the keyboards right next to each other (B3 style), in which case it's not too big a jump to the T2's controls...

Plus, a set of Yamaha control switches (there's an input for a 10 button footswitch thingy, isn't there?) can do away with a LOT of panel switching....