For what it is worth: I had a fatigue problem also and my wife took over all the towing. She started out just driving on the interstate and progressed to driving in high traffic situations and cities. The last hurdle was backing into a campsite.
Last fall she did 100% of the driving, drove over 1000 miles and backed the RV into sites!
If your wife can drive a car, she can tow the rig. A RV driving school will show here the differences between a car and your rig, but most importantly will give her the confidence needed to drive the rig safely.
Just don't look so happy when you go down the road when she is driving, and you are drinking a cup of coffee and relaxing in the passenger seat. :)