We have stayed here many many times. The last trip to Yellowstone we stayed May 12 and May 22, 2018. We have a 36' RV and tow a Subaru and have two large dogs. We have never had a problem. It can fill up in the summer on weekends and in hunting season, so you need to arrive early then. There are only 28 spaces and two Tipis. So reserve if you can. It is a halfway point for us so we use it at least 4 times a summer. A pass makes sense if you visit often, they have them for residents and non-residents.
The park has lots of large cottonwood trees and is right on the river. Info from their website:
Park Features
Visit and enjoy Beavertail Hill! One-half mile of the park is located on the Clark Fork River that provides terrific fishing and floating opportunities.
You can camp and go on a one-hour walking nature trail through a thick canopy of cottonwoods. Don't miss our free interpretive programs in the amphitheatre on Saturday evenings during the summer.
The park has an elevation of 3,615 feet and is 65 acres.
Boating is carry-in only. There are 28 developed campsites and tipi rentals.
The two Sioux-style tipis at Beavertail Hill are 18 feet in size and can comfortably sleep six-eight people. The canvas tipis have no furnishings, but do have indoor-outdoor carpeting inside, and a picnic table and fire grill located outside. Existing ADA Level: Easy Accessibility.
Take exit 130 from I-90 E, cross the railroad and follow Bonita Station Rd, the park is well marked and on your left. read more