That really is a broad location...tough spot to hunt for many reasons, let alone the mosquitoes!
Extreme Northern Mn and into the Rainy lake realm the dirt changes so rapidly...Theres Glacial morrain gravelly type of dirt around Bagley, Bemidji, Fosston, just a few miles North into Gonvick and Gully on your way to Grygla theres peat bogs, they catch on fire from lightening strikes and smolder all summer, unmistakable smell...anyway,...East out of Grygla to Northome above Red Lake, it changes again! Warroad is some sort of clay, lots of beet farmers to the west of there over by Thief River...that said, theres old dirt, cedar one room schoolhouses, Old farms and communities, RR trestles etc... lots of Indian wars and abandoned homesteads and the like..Since you mentioned Scout camps, one may assume he's thinking about over by Leech Lake area and to the South?
Id go with a Shark of somesort and a scoop and hunt the beach water, around the old homes and resorts, for old gold and silver... if a guy can tolerate mosquitoes and leeches, which most Minnesotans can..short season though, so he better get cracking! There was a guy who lived up there, maintenance man for an apartment complex or old folks home or something...'Dave' something or another maybe? I cant remember his exact name right now..He found some great old silver coins and he uses a 'Lab..
Tough call..I guess he couldnt go wrong with a Compadre right? Especially for his kids to use, being light and all, whereas a Shark is a lot heavier and designed for a specific water usage by serious gold hunters?...
full disclosure:
I trapped beaver up in all these places for the MN DNR back 30yrs ago, and as a side job, I also dug graves by hand, worked for farmers etc... in all the various tiny old community graveyards where a guy could not get a backhoe into, they had to be dug by hand...so a guy notices and remembers soil changes in field when thusly employed of course! I just happened to remember..I didnt detect at the time, but sure wish I had! That whole area is quite a strange place, no telling what he will be finding!..The Kensington Runestones are of course a lot further south, but interesting none the less? .
If he had asked you about trapping beaver, fisher, otter, Fox, coyotes, wolves, cats, ermine, mink and the like, I would most certainly be your huckleberry...damndest place I've ever lived though...I dont see how Gunnar can handle it!
Mud.