Welcome to the forum.
No knowledge of your make and model boat specifically but using a dremel or fein style tool to cut an access hole in the back of the cabinet neatly is a trick I use to gain access to otherwise inaccessible areas. Exercise caution not to cut too deep too quickly as you never know what lays behind the cabinet.
Done properly the piece you cut out can be used to patch it back with screws or velcro. Leaving a barely noticeable and very handy future access panel.
Hope this helps.
Craig - AKA Some Clueless Idiot
The person who is saying something is impossible should not interrupt the person who is doing it.