5k of climbing in 60 miles is fairly hilly but not dastardly (100 ft per mile works out to about a 2% grade, which is pretty reasonable) - my suggestion for you is to take it easy on the hills (stop me if you figured this out already ) so that you don't blow up before you hit the finish line. Wind is wind, make your wife do all the pulling. It's only fair since she signed you up, right?

Eat a nice dinner tonight, drink a lot of water tonight and tomorrow morning and go have fun - you can do it!