So you don’t mean the electrical connector and are talking about the pmag mounting nut? I found a crowfoot the right tool there. A stubby wrench might work. If you are talking about anything electrical it works best to do those with the pmag off the engine
Ser 140142, RV-14A flying - N1463
Ser 83825, RV-8 building - N8638?
USN Ret, Urologist, AME, Repeat Offender