On the West side of Glacier there quite a few from the Park Gate down Hwy 2 into Hungry Horse MT and even further on into Essex MT, I have no idea about any of them, they are not our style of camping. But seems like they are full most all summer. Columbia Falls has one that is full of BIG BUS type campers right on the Hwy!! maybe they would be able to accommodate your desires? As you drive up the East side of Glacier there are fewer and fewer because your on Private land or in the Blackfoot Reservation. If you should go on the East side do yourself a favor and DRIVE RIGHT ON BY BROWNING MT its a hole!!!! You can get cheap fuel there its just North of Browning and still on the Reservation so you don't pay taxes. I think it is Hwy 464 maybe 2 miles up. If you go to the East entrance at St. Mary don't use Hwy 89 its passable but a waste of time and VERY NARROW. Go Hwy to 464 Duck Lake Rd to Hwy 89 just south of Babb MT and go south to the East entrance the road is better and more conducive to better travel time, don't be afraid to speed out there, nobody is out there anyway except cattle. Of all the places in Glacier our favorite is Two Medicine Lake area, its the most remote of the larger campgrounds and has room for your size 5th wheel but are limited, it is a first come first serve campground. If any of the campgrounds are to be used, get there on Sunday around Noon, the campers are leaving and you will have a better chance of finding a spot. Out side of the St. Mary's gate there is one RV campground with hookups, I dont think it has a pool, but has a laundrymat, and a restaurant, its just north on the east side of the road. There might be more than what I can remember around the entire park, but like I said we don't look for those so we don't really remember them all.
Have a Great trip Glacier is a great park to spend time in.
BIG