Upside down DIY drill press for working under the RV

I would think that the resetting process for each hole would be too time consuming and extinguish the delightment of the ingenuity in a hurry...unless you are on a flat, smooth surface and can build a platform on wheels to roll the drill from location-to-location.

A good quality self-tapping screw (not Phillips head) would be my initial choice, as others have mentioned.