I broke a side window. It was the inside pane of a double pane slider, above the couch. I took the unbroken piece (to be sure the glass shop got the size right) and went to a normal glass shop, not an auto glass shop. They sent the order to somewhere else for tempered glass, but had no trouble whatsoever dealing with this. Maybe because I needed clear glass it was easier, but in the past I have ordered tinted glass, tempered, for my sundeck fence, and went to an ordinary, small shop for that too. Just ask them for glass, tempered, custom cut to your requirements, and don't scare them with "for a Motorhome".
Good luck.
Keith