Wheel Alignment and Balance in Missoula ?

Check with any of the Les Schwab outlets in Missoula. They may be able to do both these things, but at any rate they are good guys to deal with in my experience and will likely help you find the service you need.

I would not be surprised that Les Schawb is unable to help you. They are really a small-car/truck service and something the size of your 41 ft DP is probably too big.

Bretz RV, on the north side of town, is an RV dealer that sell rigs your size and should be able to help

Istate is a commercial truck service center that also may be able to help