Not that it matters that much but what year is your hull, 2000 or 2003?
The deck plate in the cabin allows access to your front bilge pump. You cannot get/see the tank from there. The plate between the helm chairs should allow access to the fill/vent hose and the fuel gauge sending unit.
Your inner hull is set up something like this:
Looking left to right, down the centerline of the hull:
The small bulkhead in the bow forms the hold for your anchor line.
The next larger bulkhead forms your forward (cabin) bilge. The deck plate resides on the bow side of that bulk head. On the stern side is where your tank compartment (coffin) begins.
The last large bulkhead separates the tank coffin from the rear bilge.
Each of these bulkheads allows water to traverse from bow to stern via a molded opening or conduit. While it's hard to see in the pic, look closely at the bottom of the two larger bulkheads and you can see the conduit. Your fuel tank sits on a platform in the center section between the two bulkheads. This platform allows water to pass underneath, again from front to back while keeping the tank dry (most of the time).
So, if you have a fuel leak and depending on the amount, you might find evidence of it in either of the bilges. Since you stated the smell appeared in the cabin, I would first look at your access there.
As to whether you could use a two part epoxy, I can't say. If the leak was confirmed but only accessible by removing the tank, well replacement rather than repair would be my first choice.
Good luck.
