If you want to camp there, you don't need the ticket for the NP. But you have to buy the ticket for the NP at the first gate about 18 km before.
The conditions for the park entrance have changed at the end of March 2017 : it is valid for 1 day and not for the afternoon before.
Showers and toilets were closed in the morning.
Place: Tikal Campground
Visited: April 20th, 2017
Location: 17.22527, -89.61132