Max is one goreous dog. I hope that he will be a wonderful addition to your family. Congratulations to you and to Max.

As far as exercising him by driving slowly while someone holds the leash, I'm not comfortable with that as a solution. First basically I feel that this is dangerous and second, it is not going to be much fun for Max. Before we got our yard fenced in, I used to attach a 50 ft. traing leash to Hannah's collar and let her run around with it dragging on the ground. I would throw the kong for her and she would bring it back. If she ever got to the edge of our property and looked like she was not going to stop, I had a fairly good chance of running and stepping on the end of the leash before she got too far. You have a much bigger dog than Hannah, so I don't know if stepping on the end of the leash would work or not.

I'm presuming you do not have any dog parks near you. What about a fenced in tennis court? I know people around here sometimes use that as a place to exercise their dogs. In the mean time, a good brisk walk with you or your husband and the indoor play, should be enough. That 50 foot leash (although it takes a little practice to manuever correctly) also lets the dog run back and forth quite a ways while you basically are doing much less. Good luck.