This is pretty backwards. If you want fewer people to visit, charge more. Charge extra to non locals if you’re so inclined. Don’t allow advertising, sure. But making parks free doesn’t make the problem better.
Charging more to cap visitors shouldn't even be on the table.
Those are the options you have to pick. Given those are the options, number 1 seems pretty darn appealing.
Ouch. The rich have enough playgrounds already.
2. Lottery or capped reservations.
Zion is just nuts at the moment. It's awesome to see everyone out and about enjoying nature but the amount of people are just overwhelming to the senses. (The park itself seems to be holding up fairly well)
5. Carefully exploit the resources for a few more trails and opportunities.
6. Foreign tourists could be charged a greater amount.
I visited Gatineau Park (just north of Ottawa) this way. I think the bus was free. It also meant we didn't need to plan a round-trip hike.
In the peak season there can be a multi hour wait and the nearby town is also constrained by the canyon and there is no more places to put in parking lots.
I don't really think there is an option besides limiting daily visitors.
These are National Parks, not state parks. Locals don't pay for them, we all do.
For example, the British Museum is free, but the donation box when leaving points out that its paid for by taxes. I've seen international tourists making significant donations (e.g. £30+ for a family) recognising what visiting a similar museum would cost in their own country. But I like that a student from a low-income country can still visit the museum, and I'm happy for taxes to cover the cost.