"How long should I let this field "rest" before attempting to set up there again?"
pick a different spot with a different setup; ie, if you had 3 decoys only put out 1, switch from box call to mouth call, etc. but as far as letting the field itself rest, nope. you already know there's a bird there, no sense going elsewhere. long as it aint the same exact setup he's walking into, you have as much chance with him as anywhere else. change things up enough so he doesnt think its you, but other than that, have at'em.
i've taken long shots before and missed myself, and go right back to it. from what i've experienced, they usually go quiet for a couple days, but that doesnt mean they cant be called back in. just dont expect him to be as vocal for a little bit.