I can't get the forward blige under the cabin clean in my 47 fountain. Does anyone know how to directly access the forward bilge. I have only been able to dump hundreds of gallons of water and bilge cleaner into the access rear of the head and this hasn't worked. It just runs into the rear and hasn't helped the forward bilge.

outside of cutting an access hole, your at a loss.

Would cutting a door in the cabin floor to access the bilge underneath significantly compromise the structure. I have seen aftermarket floor access doors for boats and have had smaller boats with them where they double as ski storage lockers

Cutting a round hole, sealing the edges and installing a deck plate is OK .
Jim