Here's another idea for the PIKANTO radio-installation. The yellow parts are 1.5 mm glassfiber boards (PCB-material) which are glued to the finbox and the mainsheet post. They would provide two or four mounting holes for M3 bolts that secure the main radio-plate (not shown) to the boat. If this is rigid enough I think no support to the sides of the hull or to the deck is required.
What's the simplest possible way to install the radio components in the boat?
Here's an idea: Use an FR4 glassfiber PCB-board (yellow) cnc-cut to the correct shape and with cut-outs for the winch, rudder servo, and batteries. Mount it to the deck with long M4 bolts with Y-head screws that mount flush to the deck. Use 50 mm long 10 mm diameter aluminium spacers (blue) to position the plate at the correct height below the deck.
Simple: yes! Works with both HiTec and RMG winch: yes! Easy to manufacture: yes!
Update: top view of a shaped radio-board:
Update 2. Here I have drawn 50mm deep U-shaped glassfiber supports that hold the radio-plate from the sides. Also, there is an L-shaped beam which is glued to the finbox and to the sheet-tube which gives additional support to the radio plate: