Tow or drive the dinghy to the mountains?

So, I am going to take my annual trip to the midwest and on the way stop at my property in the AZ mountains which is at about 7000 feet elevation. I am traveling from Phoenix which is at about 900 feet. My question is is it better to have my copilot drive the toad up the hills or drag it up there with the RV? I figure gas is cheaper towing it, but the strain on the engine/tranny etc and the slow down on the grades may make it better to just take the two separately over the first leg here.