I say we look at this from a different approach.
Those that ride off-trail only use the trails a minimal amount just to get where they are going, so they should pay less.
Those that only take one trip a year cause minimal damage, so they shouldn't pay the full freight either.
Those that ride every weekend, high-mileage riders, etc., cause the most trail damage, and therefore should pay more.
And remember, the heavier the vehicle, the more damage it causes to the trail, so Yamaha 4-stroke riders have to pay an extra fee
It comes down to user fees - yes folks, I am talking about putting up toll booths on the trails. You use them, you pay, you don't use them, you don't pay, simple as that!