If you use a simple ON / OFF function R/C Switch ....like I believe the Battle switch to be .... then you wont be able to give the crusher the OFF function.
Youll only be able to get FWD ( extend to crush ) when you activate the Battle Switch and REV ( retract and return to the ready position ) when the Battle switch is OFF.

You really want a Robbe - Duo - Switch unit #83192000 or similar to activate some larger amperage relays.
You can then get your required 3 functions.