Yeah, driving from Penn would be some hours!! You could work and extra day or two and more than cover the plane ticket minus gas.
Anyway... remember to check the moisture status of the terrain before you hunt. In wet years (we've had several lately), water hole hunting is pretty slow. Antelope will drink from the smallest of puddles. If there is green grass, they get a lot of moisture that way as well.
In dry or drought years, waters holes are a blast. In south eastern montana (very similar to much of Wyoming) the action can be nearly non stop in Aug or Sept. It has become one of my favorite hunts.