I’ve used SkinTac for Dexcom sensor applications (as well as all pump insets) for several years.
You’re completely overthinking this. I don’t care if the Dexcom sensor goes thru skin painted with SkinTac - in practical application it doesn’t make any difference.
SkinTac allows me to reset G5 sensors up to 4-5 times and still have accurate readings 5-6 weeks later.
I lay down a layer of Opsite Transparent Film dressing (on SkinTac painted skin), then coat the Opsite with another layer of SkinTac before applying Dexcom sensor. Stays firmly in place for 5 weeks, with daily workouts and showers.
I do cut a “window” in the Opsite so the sensor doesn’t need to penetrate it.
see my post here with details / photo