You can never have too many pumps.
My EggHarbor came OEM with 2 main pumps and one shower pump.
Over the years, I added 3 more pumps. Each pump has its own discharge.
So in the lowest main bilge, one rule 2000, two rule 3700, one 350 shower sump type pump.
In the aft area, one rule 2000, one rule 500 and a sealed bulkhead divides bilge into two sections.
I wired the two rule 3700 with separate water level switches, but both I turn on simultaneously with one switch and two relays.
Basically this, except I used 12 vdc 40 amp cube relays instead of diodes to prevent any voltage drops.
One switch turns on both pumps.
Each pump can independently turn on with its own water level float switch.
The extra pumps are purely 'emergency usage'.
I have them at the same basic level as the original OEM pump. I really ought to raise them a little higher.
One winter with boat in slip, the bilge froze solid. Pumps which are ice locked cant pump water, so if a leak had happened, down the boat would go. There is always some residual water in the bilge, mostly from rain.