There is no clear answer to your question. In Texas many cities have regulations regarding what can and can't be done in city parks, athletic fields, etc. For example a large suburb near me does allow model rockets in some public parks but you need a free permit.
When I was a Scout leader most Texas state parks simply considered model rockets as fireworks and said no. If the steward of the public use land says no then you have to abide by that unless you can change their mind through education.
You also need to make sure that the area isn't subject to a burn ban as are many parts of Texas in the summer and even winter months.
For your own protection, you need to clearly identify who is responsible for managing the land and find out their policy on model rockets. If the police show up you want to be on the right side of the land manager, especially in this day and age.