If you don't need electric, Wasa Lake Provincial Park is a 15-30 minute drive North of Fort Steel, and you can go for a swim in the lake after a hot day at the Fort. discovercamping.ca. You can make reservations at Wasa. This is where I've stayed since I was a kid, and now I take grand kids. It's usually hot in the summer, but well treed and so it cools down in the evening.
The campground at the Esso Station is called Fort Steel RV Park. https://www.fortsteele.com
. It is right across the road from the entrance to Fort Steel. Haven't stayed there, but would if I liked hook-ups.
Another great choice is Kimberly Riverside Campground. It has a pool and is next to the river. The folks that run it are very nice. Has lots of trees. Kimberley Riverside Campground
Fort Steele is pet friendly, except in areas where food is served. My pup loved the air conditioning in some of the buildings. Bring lots of water, and a cooler for your lunch. You can come and go from the park all day. Have a great visit there.