When we had the crank up OTA antenna I would hang the ignition key on the crank! That worked. DW and I double check each other and sometimes switch routines so she will do the exterior jobs she is physically capable of (she is not strong enough to handle the towbar) and I will take over interior routines. That way either of us can setup or get underway and we know what we are looking at when we are double checking.
We do have check lists for everything taped inside cupboard doors. We do review them from time to time but are not good about actually getting them out to follow. We have been on the road for 15 years and have usually moved a couple of times a week.
We have done all the stupids mentioned plus almost losing the tow'd by disconnecting it before setting the brake (many years ago, twice).