The hole you see back by the rudder are holes in the plastic bilge liner. THe hull and tanks are underneath that, the leak could be coming from another spot. If the leak isn't bad, I'd just leave it filling all the time and let the bilge take care of it. If it leaks so much that the bilge can't keep up or it drains significantly during a set when the inlet is not submersed, then I'd do something.
I think I would test in the driveway by tilting the boat on the trailer with a half full ballast, test in several positions to see if you can isolate the leak to front or back. Then, remove the gas tank, use the existing forward access plate, put shop lights in there to dry it out.
You can use a camera to inspect the tank, you MIGHT be able to an obvious bad joint. I know in the internal ballast pics that are in the Old Forum Pics photo album you can see sketchy areas that I would do something about if I had leaks.
You could cut a hole in the V drive storage, it would be really nice to know where the supports are in the tank. Pull the sending unit and take pics around it.
I'd cut a hole, if needed, for an 8" deckplate. I'd put epoxy and fiberglass mat down inside the tank on the hull to tank wall joint, lowest in the bilge. I'd start with the rear, as the water pushes hard back there when the boat is loaded and you are hitting double ups with five people and full tanks, etc. I'd probably cut a back hole, dry the tanks for a couple of days, Reglass as much as you can reach thru the two access plates. If you don't want to do it again, cut a hole in the storage compartment floor and do the front.
Cutting a round hole and putting in a deckplate will increase the strength of the tank if you install it properly.
I think it is an inevitability in an SX to have a tank leak. The hull is very stiff, it takes the chop way better than my Epic 22 did, but I bet, over time, tank leaks will develop. I don't think it is bad design or construction, I think that it is the nature of tanks built from fiberglass. I know the other Epics have reported similar problems, they run fiberglass tanks.
Capt Rick, do you have anything for the record on the insides of these tanks, troubleshooting and repairing leaks etc? What about HIN numbers of boats that have been repaired, etc.? Any tips on places to look at, known issues?