Thinking about heading up for some car camping and fishing in NSF later this month. Wondering if I might have trouble finding campground availability in July or summer weekends in general?

nope problem there pretty open if it’s not an holiday weekend.

Give Crescent lake a try. It's just south of Baker lake and not too far south of Brule. Reserve-able sites and think there may even be a couple of paddle in only sites. I'd have to look through my notes I keep on each campground we visit. But I think we were at site 23? Looked the best of the campground.

Consider Two Island Lake as well. Some real nice sites right on the water. Arguably not quite as pretty as Crescent but better fishing.

We stayed at Birch Lake outside of Ely in early June and that was pretty nice too. Some real nice sites and a good fishing reputation.

Recreation.gov lists all the campgrounds. You can see maps and photos of sites, including which sites are available, and you can make reservations where possible. It will also show which sites are first come, first served.

Superior National Forest Campgrounds

Thanks all, this is very helpful. Appreciate the replies!

Don't overlook the Rustic Campgrounds
Rustic campgrounds have fewer than ten sites and there is no charge for camping. Facilities include outhouses, tables, and fire rings but there is no drinking water or garbage cans. Sites are generally for tents, but some will accommodate a small RV or tent trailer. These campgrounds were often developed with fishing in mind, so be sure to pack your poles. Most rustic sites are located on the Tofte Ranger District and in the Isabella area.

Maximum group size of nine.
Only use the facilities that are provided for fires, tents, and waste.
Do not make additional fire rings, tent pads, trenches, or cat holes.
You will need to pack out your garbage.
Quiet hours are enforced at developed campsites. Be aware that sounds from your campsite including radios, generators, or musical instruments should not disturb other campers even outside of quiet hours.
Follow the links below for more information on individual campgrounds.

Campground Camping Areas
Gunflint Ranger District
Cascade River Rustic Campground
Devil Track Lake Campground
East Bearskin Lake Campground
Flour Lake Campground
Iron Lake Campground
Kimball Lake Campground
Trail's End Campground
Two Island Lake Campground
Kawishiwi Ranger District
Birch Lake Campground & Backcountry Sites
Fall Lake Campground
Fenske Lake Campground
Sand Lake Rustic Campground
South Kawishiwi River Campground
LaCroix Ranger District
Echo Lake Campground & Backcountry Sites
Lake Jeanette Campground & Backcountry Sites
Laurentian Ranger District
Cadotte Lake Campground
Pfeiffer Lake Campground & Backcountry Sites
Whiteface Reservoir Campground
Tofte Ranger District
Baker Lake Rustic Campground
Clara Lake Rustic Campground
Crescent Lake Campground & Backcountry Sites
Divide Lake Campground & Backcountry Sites
Eighteen Lake Rustic Campground
Fourmile Lk Rustic Campground & Backcountry Sites
Harriet Lake Rustic Campground
Hogback Lake Rustic Campground & Backcountry Sites
Kawishiwi Lake Rustic Campground
Little Isabella River Campground
McDougal Lake Campground
Ninemile Lake Campground
Poplar River Rustic Campground
Sawbill Lake Campground
Section 29 Lake Rustic Campground
Silver Island Lk Rustic Campgd & Backcountry Sites
Temperance River Campground
Toohey Lake Rustic Campground
White Pine Lake Rustic Campground
Whitefish Lake Rustic Campgd & Timber-Frear Area
Wilson Lake Rustic Campground & Backcountry Sites link

Thanks BearClan, really like this idea and plan to check out some rustic sites.