if you do the split version as HUD suggest (or buy one) make sure your motor
will fit over the thickness easily. My yamaha 15 barely, only if forced, fit over the total thickness on a purchased plastic version. It was the bane of my existance for a couple of years cruising! Frankly I wanted my homemade one like you suggested back! Another hint if you make or buy one: If possible get one as close to the thickness of your dingy transom as possible. Not matter how much you lubricate them, those outboard
tightening screws seem to get hard to turn. so the less turning the better!