I picked up a set of RVMinders at camping world. On sale for $9.99. They slap around the steering wheel and have preprinted items on most and a couple blank. If I open a window or vent, SLAP goes the Windows/Vents/Doors strip. When I turn on the propane, SLAP goes the custom Propane strip. If I hook into electric, SLAP goes the Hookups strip. When I get ready to drive away, I do a walk around, then one by one remove the strips from the steering wheel. If I have any hesitation, I leave that strip on the wheel, do another walk around, and then remove it.
I find it works a lot easier than checklists, etc. and compensates for my forgetfulness because there is no way I can miss that strip flopping around on my steering wheel.