When you see a Town Pump, convenience store and fuel, they usually are RV friendly. Dump and potable water. Also they usually have the cheapest fuel and gas. A very good operation and only in Montana with many locations.
We stop at Cabela's in Billings, MT. They have big rig parking, fresh water, and a dump station. There's a $5 fee to dump, unless you buy something in the store (ask the cashier for a code to use the dump station.)
Another benefit for using Cabela's is a Sam's Club store next door.
Tom
2015 Meridian 36M 2006 CR-V toad 3 golden retrievers (Breeze, Jinks, Razz) 1 border collie (Boogie)