Should probably keep my mouth shut since I'm not familiar with the Epic d-drive.
My bilge pump is mounted midships, right next to the drivers' feet. The low spot in the hull (when sitting still or while trailered,) is right there. Kind of anoying because pulling the drain plug only helps if the nose of the trailer is sky high.
On plane, the transom will be the lowest spot and a forward-mounted pump won't have any water to suck.
The biggest deal is your mention of water in the tranny area. The engine, exhaust and tranny (also v-drives for SX and S22) are all cooled by sea water, which is under pressure. If you've got a leak in that system somewhere, you've got some important fault isolation to do. A leak in a cooling system means something's not getting cooled like it should. Find it, fix it, or you may be replacing more than a bilge pump.
On a related note, I understand the Owner's Manual descibes a three-position bilge switch, bu mine is clearly either armed in the auto mode, or off completely. Just might double check that. Click it once and the indicator turns red and if there's water in the bigle the pump will spew until there's no water then turn off. Press the button again and the indicator extinguishes and the pump will never pump no matter how deep the water is.