Hi Ryan: I am in the process of totaly rebuilding a 1977 B15. I have posted numerous pics of the process under the posts "my 1977 B15". Rick N has also done a rebuild on a 1978 TM15 Beachcomber
. All these pics should give you a good idea of where the wooden framing is located behind the panel board. I have been considering the same table hinge as you are. For me it will still be possible to reinforce with another board behind where the hinge will fasten. The hinge should only need to support the table and contents weight
. When it's turned into a bed, the weight
will be on cleats fstened to the edge of the seats.
Hope this helps.