Thanks for so many helpful responses. We were lucky that it was a T fitting that came apart in the water bay. Not easy to get at, but at least it wasn't inside the walls or in the slide. Fixed at home in the driveway in about 5 hours (We work slow).
While apart, we found another fitting that was leaking. And, the 110v outlet in the water bay (domb to install one there) was sealed on the front, but the box was not sealed at the back. All fixed now.
I ordered a $50 Camco regulator with a built in gauge. Not sure if that qualifies as a "good" regulator, but the next better at Lowes was oversized, $100 plus gauge and fittings. The extra cost and install time didn't look like a good way to go.