Welcome to the forums and congrats on getting your new Montana. That's a nice one for sure.
Here's something you might want to consider and nip-in-the-bud before you start out with that camper. That specific design has one problem that a lot of folks complain about. And that problem is, the rain gutter spout near the entry door for the rear slide out. Some folks have problems with that spout shooting water right at the door and under the awning when it rains. You might test it out with a garden hose on the roof and see how water flows from that gutter spout before your first heavy rain. They make gutters that attach to the spout and then actually hang down, attached to the side of the camper. This makes the water shoot straight down and not "outward."
Yours might not have the problem. It looks like in the photo, the spout is behind the arm support attached to the wall, so that might deflect the water. Still, check it out now. You'll be glad you did later.
Good luck. Happy camping, and again .... that's a beauty!