OK, lots of variables here. Someone said 60amps and now 36amps. Won't that take twice the time or at least more time to charge? Again 2 Costco GC.2s.
Found Intermatic FF4H 4-Hour Spring Loaded Wall Timer, Brushed Metal $29
P.S. Thanks for the specific name on the charger. Don't mind spending a little more on a 60amp (not $500 I saw online) if that will work better but what is the name and model
P.P.S. This looks like it would simplify maintenance:
Flow-Rite RV2000 Pro-Fill RV Edition 2 Battery Kit