If I was coming from Okmulgee, i would take 75 around 244 and get off on Delaware. Head south and as soon as you pass 11th, just on the south side you will find plenty of options for parking.
You can also turn left (east) on 5th place off of Delaware and park at University UMC for $10. It’s across the street from a shuttle stop which will drop you at the stadium or at tailgate and events area off of 8th St. I usually park in one of the on campus apartment lots which usually have plenty of spots. Campo is too tied up with the game to enforce any parking regulations on campus.
Depending on what time you arrive there are options across 11th St for food and drink and plenty of good options inside the stadium for the same.
There will be plenty of parking. If you don't want to pay, the neighborhoods around TU allow parking on one side of the street. Expect a 5-6 block walk and all will be well.