You had me going with the red herrings about being "old" and operating "sport pilot". Yes, the anticollision (a/c) requirement changes with aircraft type certificate issue date and manufacture date, but I couldn't find where the pilot certificate of the PIC affects the required equipment. Macht nichts. It does not have a standard category U.S. airworthiness certificate, so a/c lights aren't required for day VMC under CFR 14 91.205.
So. You don't have the system installed because the wiring is not completed. No problem. Not required, and you knew that.
You're flying E-AB, and I haven't found a CFR requirement for E-AB to comply with standard category requirements like switches AND cb's. So you install the c/b's and only set them when you need the lights. Fine. But. You're going to wear the a/c cb out turning it on and off all the time. "But I don't use the a/c lights!"
CFR14 91.209(b). If an a/c system is installed, it must be used. No mention of aircraft age or category of airworthiness certificate. If installed, must be used. Exception - if PIC determines safer to leave it off. Also, AIM 4-3-23.
So. No switches, just c/b's. Leave the nav light breaker out, the a/c cb in all the time if that's what you want to do. a/c will come on with the master, go off with the master. You're only operating day, so it won't blind anybody. Pull the breaker if you need to have the master on during maintenance for some reason. You'll also be more likely to notice if you left the master on after shutdown.
I may have missed a reg, so this comes with no guarantee.