Are there any fees if I camp out in the bed of my truck?

You have to pay a park entrance fee. There are camping fees which include that. I do not believe they will let you camp outside of the campgrounds areas so you have to pay to camp.

Daily rate for non pass visitors.

Yes; park entry fee applies.

Yes. Call them an they can help you out.

There are areas you could camp in the bud of your truck, but there is still a camping fee.

The campsites have rental fees

They have specific areas for camping I don't know if you have to pay to camp tho