It can be done but there are a few things you may want to consider. Is the bedroom ac ducted? If it is you would have to replace the inside panel or be able to run thermostat wires. Is the garage area wired for ac? If not you would have to run wiring to the breaker panel, not always very easy. I'm guessing you have an ac unit over the center of the RV. Will that unit be able to cool the bedroom adequately? It might be easier to purchase a freestanding ac unit to use in the garage.
2012 Keystone Cougar 321RES