When I was 19 I hitchhiked from Alberta to southern Ontario. I caught a ride on a big moving van just outside Regina that took me most of the way. This driver was sleepy and needed some help. First he wanted me to drive and I refused, not knowing how to drive an 18 wheeler. I did agree to keep him awake. I yelled quite a few times and almost grabbed the wheel several times. Finally he stopped and slept in the sleeper behind the cab while I caught some z's on the seat.
DW has yelled at me a few times over the years. One thing about a small motorhome - it is usually very easy to stop and nap or walk to refresh. But I got caught really bad last trip on the boring highway between Grande Cache and Grande Prairie in the mid afternoon on a hot day. We had relatives following behind us, there were no interesting or even convenient stops due to heavy rain earlier. DW didn't want to drive because there was a lot of wind gust making steering difficult. She fell asleep. I woke up when the right hand wheels of the MH dropped off the pavement with a bit of a thump to perhaps a foot down the side incline. I was very lucky there wasn't a steep dropoff and I got back on the pavement in ten seconds or so.
I am resolved not to drive sleepy again, no matter how inconvenient or embarrassing. It was really embarrassing to confess to the niece and nephew driving behind what I had done. Curiously, DW was so impressed I got us back on the road that she forgave my lack of judgement.
I think the OP's idea of preparing his family to help is sound. Of course better to have a second driver. Maybe wise to give up RVing without one. I urge him to be aware of how he feels all the time and get off the highway frequently for practise and rest.
