I use Sawyer permethrin. No, I do not use it on waders, but yes on clothes that go under waders. Ticks that jump on a wader have to get up to my chest and touch my shirt before making their way to my skin, and there they shall die, lol.
Permethrin is not a repellant like DEET. Permethrin is an insecticide. It kills them. It's the same stuff they spray in swamps to kill mosquito larva. Also the same stuff that's in flea and tick collars, the shampoo for lice, and the like.
I spray all my outdoor pants and shirts each spring. It says it lasts 6 washings or whatever. By the end of the summer it is likely wearing off and I should re-apply it, but I usually slack on that. Need to do better. But it's definitely one of those late winter/early spring rituals when you have severe cabin fever and you restock and re-organize the fly box, clean fly lines, patch waders, tie new leaders, etc. Taking a clothes rack out to the driveway and going to town with a bunch of permethrin spray bottles, and having your neighbors think you're nuts, is one of them.