My father in law in Baltimore has a basement sump that was very underrated in heavy rains. It was 120VAC and if the power went out he was a flooded basement.
I talked him into a small inverter/charger, 3000W that has a small contactor for a seamless transfer to the inverter if the power goes out. Normally closed circuit, until the power goes out, opens and transfers to the inverter, creating 120VAC for the sump.
Inverters are used all over the world with inconsistent primary power. Just some golf cart batteries, preferably 24VDC, can create a reserve capacity to run his now 3500gph sump even in a heavy rain with no primary power.
No basements here in S. Fl., but boats, and hurricanes are a great resource with no generator needed.
Sounds like your pump is plenty big.