I’ve been lucky enough to have been on about 16 fly-ins in my life, and everyone here’s generally got a good idea of what to bring. We bring a pump-handle water filter just to get all the extra crap out of there, although some years it breaks and we just go the boiling route. I would highly recommend Crystal Light or similar packets to add flavoring.
I’d definitely also recommend the mosquito coils or a good Thermacell, especially in the bedroom for a little bit before you go to sleep, unless you want to lay in bed hearing the buzzing and swatting at them all night. Although how well the cabin is sealed will really make a difference on the bugs you get. Mid-August they’re usually not too bad, at least comparatively.
Since you’re only going for a few days, I’d probably just bring one change of clothes or so, along with some lightweight long underwear, a hoodie/jacket, and lightweight rain gear, just in case. We’ve been on trips in August where we were using the wood stove every night!
As far as lures go, I honestly haven’t used anything other than 1/4 or 3/8oz jig and some Gulp for probably the last five years for walleye, unless I was bored with catching them that way and wanted to try something different. Just pick up a few packs of each size (chartreuse, gold, white, pink and orange) and a few packs of Gulp twister tails (chartreuse is pretty much my go-to, but I’ve also used white and their mixed colors with success), and you’re set! Other guys will use bait, but since you can’t bring salted minnows across anymore, we don’t bother.
If you chase pike, just bring plenty of leaders, spoons, spinnerbaits, and pretty much whatever else you want to play with! I always add a few vibrating crankbaits like Rattle Traps or Rippin Raps, I do really well with those.
Good luck on your trip, I’m sure it’ll be a blast!