adding storage space

I’m thinking about trying to add some cabinets along one side of saloon above the backrest in my O’Day 26. Had anyone done this? And if so how did you attach them? I would love to some photos for ideas as well.

I live aboard full time. This boat is well equipped with a galley, fridge/icebox, built in HVAC system, 2 batteries, a fresh water tank, water heater, head, and v-berth and aft cabin. However, one of the closets holds the hvac system, one settee in main cabin holds the fridge compressor and pump...