Welcome to the forums! (I think I might have suggested you come here from the Facebook group.)
I also
strongly recommend doing at least a short backpacking trip somewhere else before coming to Isle Royale. Learn your gear (wherever it comes from), discover what works and what doesn't, see what you forgot and what you don't need. I don't know good options in Minnesota, but a 1 or 2 night trip would be ideal. In Michigan's Upper Peninsula, the Porcupine Mountains would be an excellent beginning trip that is fairly accessible from Minnesota. This is especially true since they have some rental cabins that you could use to approximate the Isle Royale cabin experience.
I'll also reiterate doc's suggestion of staying in a cabins in Windigo or Rock Harbor. Not cheap, but makes life considerably simpler. Also, read the Greenstone newsletter thoroughly -- there are some surprises on the island, even for experienced backpackers.
If you're set on backpacking, you should borrow as much gear as possible. It's likely that you have some friends who will loan you some items, or can find a hiking group nearby that will let you rent them. Even if money is no object, if you buy a full kit of gear, you'll end up with a lot of stuff you will discover doesn't quite work for you and will want to replace.
Here's a concrete suggestion for something you could do on the island, beyond Windigo/Rock Harbor cabins:
- Take the Voyageur II from Grand Portage and stay on it until McCargoe Cove. Grab a shelter there and set up camp. There is a 3 night stay limit, so you'll have plenty of time.
- Spend a day or two day-hiking to places like the Minong Mine, Chickenbone Lake, up to the Greenstone ridge, etc. Swim a lot. Enjoy the (rare) fire pit. Fish in Chickenbone. For a longer day hike, go to Lake Richie and fish there. There's plenty to see and do just within day-hiking distance of McCargoe.
- Jump on the Voyageur II again and take it to Rock Harbor (it only goes one way -- clockwise -- so you will have to do go to Rock before heading back home). Stay there overnight, cabin, lodge, or another shelter if you want, and day-hike Scoville Point. It's one of the best trails on the island.
- Get on the Voyageur II again the next morning and head back to Windigo, then home.
This would give you a relatively easy introduction, keep you near people at all times, but also get you away from Windigo and Rock Harbor to see a bit more of the island.
Another option would be to stop at Windigo, stay there for a few nights with perhaps a dayhike to Grace overlook, and then do an overnight hike to Huginnin Cove (where there are only tent sites, no shelters).
About the Voyageur: You need to make exact reservations for where you will pick it up and be dropped off. You can't just decide to get off (or get on it) without reservations -- so it requires some planning ahead. In particular for being picked up, the Voyageur won't come in to some stops unless someone reserved a pick-up ahead of time -- so you can't count on it just appearing.
Same for cabins and the lodge at Rock Harbor: These need to be reserved well in advance. On the other hand, shelters and campsites can
not be reserved -- it's first-come, first-served. That said, you can usually find something and always have the option to share a tent site.
Lots of information -- let us know what questions you have!