So, are you really only trying to make the decision based on towing up a hill? There are tons of other considerations. If you check out all the reports on the RAM 1500 diesel towing, you will have noticed it has had no problem towing more weight than your trailer up hills, and gets great mileage doing it. Literally double the mileage according to one review. If you stay within the guidelines of the owners manual, I don't think you can go wrong.
Frankly I wish I was in your shoes right now. I'd buy the diesel GC in a heartbeat. Since it would be my commute vehicle and my tow vehicle, it would pay for itself in couple years at the most, and the rest would be gravy. (That's MY case)
