Reinforcing cabin walls for outriggers.

Hi, I'm a new guy here and have a question on the best way to reinforce the cabin walls for a set of Lee 20 ft. spreader outrigger's on wishbone brackets. I purchased a 1998 World Cat 266SC from a fellow in Florida, he was the second owner and did not use the outriggers. When the outriggers are open the cabin walls flex big time and are going to start cracking. The support at this time is the cabin wall and a 1/2 inch piece of starboard. What would be the best fiberglass material to use and what weight ? I can't go any thicker then 1/2" or the cabin panels won't go back in place. Should I use any plywood in the project? I have done a lot of glass work on boats but I want to be sure I do this right. I can also run some L brackets as the tops of storage lockers are at the bottom of the walls and I can also reinforce them and run some aluminum or other material as L brackets. I currently use the west epoxy system and find it to be very strong and easy to work with. Should I stay with the epoxy or use a different resin? Any help would be greatly appreciated.
Thanks in advance.
Obow