Parks aren't difficult to manage remotely and you shouldn't have a problem running a 40-60 lot park while keeping your full time job. Having an on-site manager to handle collections, inquiries, tenant issues, etc. is important. I have a 125 space park that is 73% occupied in the Louisville, KY metro and I live in CA.. It takes about 4 hours a week to manage.
I'd say it's reasonable to buy a fairly turnkey park and get 20% CoC returns - probably immediately.