I'd happily pay $10 a car to stay at somewhere like Knockwood with its clean new Toilet a block. I'd be wanting a second block though I think during the summer when it's busy.
If they want to offer Hot Showers then that's great. User pays. $5 a shower. Timed.
I'd also pay $10 a night per car to stay at the Comet Flat Camp ground at Woodspoint.
I agree with Cuppa though, once introduced its a snowball.