Don’t let him eat the poo. Dog poop has parasites and it could make them sick. My sulcata has had many poo incidents and has never had a problem, but it doesn’t mean it can’t happen. I pick up my dog poo daily but i do sometimes miss it. Yuck.
Don't take your tortoise to the park and don't let him run loose. Its not safe, you can't make it safe, and a million things can go wrong. You found one thing, 999,999 things to go...
Make him a large enclosure and let him run around inside that.