Most of us don't really have the funds to just buy land for our dogs! I'm sure your dogs love to run on your 80 acres, but that is not an option for me or for the average dog owner.I would hate to be the next folks to play tennis. Imagine the dog do do that would be everywhere. Seems like they love to leave their marks. I wouldn't suggest going to the Tennis courts. Buy some land and fence it in. I took my girls off their chains and placed in large kennel runs. They love it. Plus I take for walks and just let them run. I live in the country and have over 80+ acres. They enjoy that.
A responsible dog owner would certainly clean up any mess that their dog made at a tennis court or anywhere else. Luckily, our dog will not go in a strange place, but I know this isn't the case with all of them!
Kris