Mat Mat and I belong to the Rocky Mountain Canoe Club.  We do day-trips with them and some more extended trips.  One thing you learn there is who you get along with and who you don't, so that when you want to do a Quetico trip, you know some people you might be compatible with.  The umbrella organization is the American Canoe Association, I think is their name; they have local clubs all over the U.S.  Try their web site.
Last year, I took an old college buddy on a Q trip; turns out I might have been better off solo--he ended up not being able to portage well and not being able to paddle well.  I have a trip report elsewhere on these pages.  So your concern is a legitimate one; you are smart to try to raise the question.  You need someone who can help with the portage, help with the paddling, help with the camping, help with the cooking, and you can get along with in close quarters.  The canoe clubs emphasize safety and planning, and that filters out some of the idiots who think that is stupid.  Anyhow, that might be a start.  Oh, when you go on their web site, pay attenion to the focus of the local clubs--some are into SUP and sea-kayaks more than canoes--even though the word "canoe" somtimes remains in their name.  But I have had good luck with our local club and have met a lot of nice folks who enjoy paddling and the outdoors.  I plan on leading several of them on a Q trip this coming Labor Day.