Thanks for the suggestion - I called Thor and got the structural diagrams. For the area I am talking about there are two horizontal 6" wide 1" thick plywood blocking pieces. Not sure why the second one which is shown at a lower position, but the upper one is right where this arm rest is located. I plan to just go over the interior surface with lauan plywood with a box to the inside which will go from the floor up to the underside of the arm rest to be the actual support. Hopefully will find and screw the lauan into the lower plywood piece but the main support will be from the floor and not the wall anyway.
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