Cindy,
I live a little closer to the medical center than you guys do, but I drove myself to the radiation treatments most of the time. The only risk that I see is if he gets drowsy from the pain patches. I was not married at the time, but I did have my mom and sister nearby and friends who offered to drive, but most of the time I just felt like doing it myself, so I can understand.
Also, if you husband gets the PEG, it is very easy to get both hydration and medication through the tube. I used to inject liquid vicodin or dissolve vicodin tablets in water and inject it into the feeding tube.
I think that it is good for you to go out. If your husband is anything like me, when I feel lousy, I am just fine without company, and you need the break Cindy.
Take care,
Danny G.