When we lived in the Modwest, we took 10 trips or so into the Boundary Waters on multi-day trips. We also had a few times with day trips. Near Ely there is Fall Lake campground. Definitely has some nice sites, both reservable and non-reservable. I would recommend reservations. The campground sits on a lake which is nice with good fishing, but I would recommend heading to a Lake One for a day trip. More intimate waters, lovely scenery, and good fishing. Be prepared for mosquitos in camp with screen rooms and mosquito repellant. They aren't bad on the water, but you have to get there first!
Sawbill and Baker are very nice spots, but definitely don't have as many spots for a big rig.
2014 Outdoors RV Timber Ridge 240 RKS
2015 Ram 2500 Diesel