I remember when New England would use a 4TE offense in goal line situations. Granted the Cowboys dont have a Gronk and/or Aaron Hernandez type super athlete they do have 4 players who are 6'4 or 6'5 240-250lbs that would allow you to have two plays called depending on the personnel the defense puts out there. They want to put LBs in there to protect against the run you explode the formation out and have 3 or 4 1v1 matchups to exploit. I'd keep Mckeon at the traditional TE spot and break the other 3 out wide, and have Dak throw it high.
If they want to protect against the pass and go with a lighter package or try to put an extra player in coverage you have the blocking advantage. Could even be a great option formation for Dak.