Mountains aren’t really a problem — it’s the valleys that are an issue. You will have great range if you’re on the top and lousy range down at the bottom. If there is a repeater on top of one of the mountains then you will have a pretty easy time on 2m or 70cm. You can check for repeaters in your area using this site. If you don’t have a repeater available you won’t have much luck communicating from one valley to another if a mountain is in the way.
What kind of antenna are you trying to disguise? I suggested a magnet mount for the vehicle so you can just keep the antenna put away when you’re not using it. If you’re talking about HF antennas there aren’t too many great solutions if you don’t have trees nearby to string them through.