When drilling the frame put a limiter on the drill bit that will only allow the bit to just clear the inside of the hole. You are going to have to use at least 3 different bits 1/8 in. 1/4 in and then a final for the selftapping bolts.
If you do not have a limiter you can make them by cutting some small tubing that will clear the outside of the bit and chucking the bit so only 3/16 or so is exposed. Now when you drill the tubing will limit the depth the bit can enter the frame.
Odds are the wires a laying on the bottom flange of the frame and you could not hit them but this will insure that.
The gas line have to be moved just move them and rehang as necessary.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles