Put a few wires through each hole. Use several holes if needed. Cover each with a "Clamshell Vent". Perko makes a few sizes -- that's what I used, with opening downward. Not completely water tight but it covers the holes, looks neat, hides any caulk, keeps the rain and spray out, and lets the wires through. If the cockpit ever fills that high I won't worry about a few ounces that come through.