We will be replacing the black tank valve in our 2019 303 RLS. Looking for information as to the location of the valve. Would like to cut the coroplast in an "X" and/or "H" pattern in the valve area and not sure where to start the cuts. We have looked online for a plumbing schematic and can't seem to find one.

Thank you for any and all advice if you have walked through this fire on a 303!