Wisconsin Trail Pass
Too bad this can't just be tied into the registration. I assume for the most part, people who have snowmobiles ride the trails at some point. Not a fan of buying this every year and adding a new sticker, rather just have it all together and be done with. Maybe a custom colored registration sticker for those who include the pass or something.
The first place we stopped a warden asked him for his receipt as he didn't see the sticker on the windshield.