Just as with transponder certification, pitot-static tests, etc, DAR's do not have the equipment to verify compliance. It is up to the operator to insure that the aircraft meets the requirements for the particular flight. When I inspect an airplane if it has lights, I do make sure they are working and installed properly, such as the red nav light on the left wing (yes, I actually found one that had the green one on the left wing!). If they happen to be home-grown lights, I will make the comment that there are regulation requirements to be aware of, but that's as far as I go.
Phase I is all DAY/VFR anyway. The person may never even fly it at night, and justs likes the extra "visibility" of having position lights.
The bottom line is that the "guidance" you sek is in the FAR's already.
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
EAA Homebuilt Council Chair/member EAA BOD
Van's East Coast Representative