The standard theory of "they won't come through thick vegetation" just doesn't hold true..........at least not all the time. If they want to come, they will. I've seen turks come through amazingly thick stuff. Heck, I've seen them walk through water up to their chest down here in Florida.
On the other hand, why make it hard on them? Next time, set up where he won't have to come through the tall field. Try setting up on a corner where whatever side he walks down, he can just walk the edge to get to you.
I'd set up back in the woods with a decoy out near the field, preferably up on a log so the tom could see it over the tall vegetation.