To me, a fee would be simple to implement, and enforce.
I buy my hunting/fishing license online. It is mailed to me. I have a printed receipt if I need to hunt or fish before I receive the license in the mail.
Same system can be set up for a boondocking/Public Land permit. One for Federal land, one for each state. If someone only wants to camp one weekend of the year, they could buy a 3- or 5-day pass, similar to a short-term hunting or fishing license.
Where you cross-over from Washington to Oregon, for example, just have two permits. Or, have each state's permit valid in neighboring states, but only within 25 miles of the state line.
I think Dan's idea is fine. I would be willing to pay $75/yr for a Fed pass. I already purchase a Colorado State Parks pass, so I can enter all those parks free - just pay the nightly fee for camping.
And, Dan, I would join your Pro-fee group.
