I have mixed other behaviors with physics by doing the following:
A: platform behavior, physics with Inmovable set
B: solid attribute set, physics with inmovable set
C: solid attribute set, physics with gravity
D: physics with gravity
C and D fall and bounce off B as expected
A can stand and jump off B as expected
A may stand and jump off C but C doesn't react to it
A doesn't react to D, however D is pushed as if A had infinite mass.
I've used a physics proxy before, but that didn't go so well. You could try it. Or go the all-physics route. They're both hard.