While Battue's comment about "salting" the fields is accurate, its also true that stocked birds will wild up in all circumstances. Some take longer than others but it does happen. The more wild birds around, the sooner and easier the parolees will take on their behaviors and attributes. For what its worth.
There are pockets of birds all over the state. A friend told me today that he went out Friday with a group near Milbank. Milbank is way out of the pheasant belt, like 100 miles out. Yet they found a pocket of birds and shot 'em up two weekends in a row. You might find that a good option for you is not in the traditional Mitchell-Chamberlain-Winner-Pierre areas but further north or west or northwest of there.
Dogs are critical to your success, don't discount that. Would you hire an elk guide with no optics? No. No one who knows much about pheasant hunting or does it often would do it without dogs. You have to put up 2-3 times as many birds in front of someone to fill his bag limit. That isn't good for anyone, certainly not the hunters.
IMHO, a guy from out of state with no connections will have to put in more work than its maybe worth to find a place with "all wild birds." YMMV. I think people make it a bigger deal than it is. Every once in a while I'll find one in our bags even where none should theoretically be found. But you should know what you're paying for. I think you're on the right track. Call around and see if you can find a guide who doesn't have his own place but who has arrangements with landowners. Such a guy would be less likely to put out released birds, but it still might happen. No one hunting wild birds will hunt the same plot more than once a week. Or should, anyway. That should be a tip for you.
