Buy a really good compact led flashlight instead. After 6 years, 2 -3 oil changes a year I can usually get the stick in the hole first try. (My wife is a witness). You are asking for trouble putting a hole in the cockpit floor. Alignment, size right on the first try ????; centering the sucker on the second try; cost of a good fitting, Sikaflex, and 5 + hours later and you've spent more time than at poking the oil stick for the next 10 years of oil changes. Plus the hole in the sole will leak and compromise the balsa core (guarranteed in the next 20 years). Your biggest leak issues will be over-winter storage with a tarp leaking and freezing water!
Weather or Not (aka: "WON")