Big Moose Lake trail is about 3 miles long and it ends at a nice campsite on the lake. I was last there about 5 years ago. There's a sand beach at the campsite. If that camp is taken there really is no other option.
Brule Lake trail connects to Eagle Mountain trail. I don't think there are any campsites on the Brule Lake portion.
Sioux Hustler is about a 32 mile loop. It is pretty rugged as the trail clearing groups don't get there often. I walked about 1/2 of it last year, lots of fallen trees to get around. I liked it but be prepared to get into some gnarly messes.
These are not trails in the sense of a state park trail or the Superior Hiking Trail and I wouldn't call them a cowpath either. Parts of the Sioux Hustler trail are indistinguishable from a game path though. The Big Moose Lake trail is pretty much open. When I was there some canoeists were using it as a portage.
That's the Sioux Hustler trail at the cairn which marks the campsite on Agawato Lake.