How would a couple stripes of hysol work on the back side of the panel?
Apply like torque marker paint.
I just tightened the nut on a non-keyed hole and its been fine for 4.5 years.
IMHO those stories about the ACS multi-position switch causing failures are MUCH overblown. Just install everything right and make sure you install the called for capacitor AND the called for diodes on the master relay and the start relay. I have not had any trouble and the factory SLSA's have been doing this for years without trouble, and as far as I know are still doing it. Now if you want the flexibility of turning the engine without ignition on (which I have never once found the need to do so) then use the toggle switches.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
Turning the engine on the starter without ignition is something that should be done on every oil change to confirm oil pressure prior to the first start. Pulling through by hand to burp does not confirm there isn't an air bubble in the system.
Brett at LEAF, a friend of mine, told me they have replaced dozens of these switches at their maintenance facility on certified, S-LSA as well as experimental planes due to failures. That was good enough for me.