I too would try to remove (tiwst off) the faceplate first and see if that gives you enough clearace. Most hardware stores should sell brass and maybe stainless steel 1/4 inch NPT fittings, I would use a short 1/4 inch nipple (1/2 inch long maybe, or maybe even a close) add a 1/4 inch threaded coupler onto the end of it and screw the new gauge into the coupler, even with a close that will add around 1/2 inch to the overall length which I suspect is all you need.
Ike
p.s. out of the big box stores I have found Lowes tends to have a better fittings selection than Home Depot, but I don't recall seeing stainless fittings at Lowes, if you have an Ace Hardware nearby I would try it first.