We had a similar problem on a trip to the Oregon Coast. I got out through the driver's door and missed the "stirrup" step. When I felt myself toppling out backwards with my head about 9' above a concrete pad, I grabbed onto the door-frame and managed to pull myself back up, causing major damage in the process.
There's no way DW can drive our rig - she can't even reach the pedals. Fortunately, one of our dogs had arthritis and we had a full bottle of Tramadol pain reliever with us. I took most of them during our 3-day return trip! A month or so later, I had spinal surgery to repair an extruded C4-C5 lumbar disk.
I use the driver's door as little as possible nowadays and never without a step-ladder outside. BTW I'm about 7 years behind you age-wise and have other arthritis-related problems! I think we may be giving up the RV lifestyle and selling our rig in the spring, particularly if the State Legislature puts another 11 cents on the gas tax, as they're threatening.