I liked the CA prop a few years ago that pushed fees into your vehicle registration and just made it free to arrive if you showed a registration.
It would have made the parks a lot more sustainable in terms of revenue and increase the quality while making it cheaper for anyone who went more than once or twice a year.
I don't think this is a great solution. For one thing, it favors car owners, which would discourage many people who live in Denver cities and people who have particularly low incomes. For another, it's not really a fee for the parks anymore when people are obligated to pay it for something largely unrelated. That's more of a tax, and while I wouldn't have a problem with paying it myself, it moves away from the current status quo that people who use the park help pay a little more for its maintenance. I think that's alright in principle for public wonders like the parks, but focusing the fee on car owners seems a little arbitrary.
It would have made the parks a lot more sustainable in terms of revenue and increase the quality while making it cheaper for anyone who went more than once or twice a year.