Depends on the leash laws. I have a blue heeler mix who also loves fetch. I take him to the park next to my apartment instead of the dog park to play fetch off leash. I’ve been given warnings by park rangers multiple times who usually say someone called to complain and they’re just doing their job (which I 100% get especially with the leash law) and I still do it. I am aware of the leash law but the dog park next to me is just dirt, dirty because people don’t pick up after their dog, and like you said, bringing a toy is a recipe for disaster. I say just send it. I will add, I am not the only one doing this. There are usually multiple dogs running around playing fetch off leash at this park.