I didn’t make a reservation for Toroweap when I went last year. A buddy said it was first come basis, then I saw the sign on the way in and tried to navigate the reservation website with limited cell service. I gave up and decided to head in and stopped at the ranger station about 10miles from Toroweap. They can’t tell you if there are openings but issued me a permit and told me if it fills up with preregistration campers I had to leave. Luckily only two others showed up to camp. There is also BLM land just before you enter the park that is open camping.