Replacing a flat TRAILER window: is auto glass what I need?

My front window cracked, spontaneously. Nothing hit it. One morning, there was a little crack working in from an edge. I covered it with duct tape (we were on the road.) . The next morning, the crack extended across the narrow dimension of the rectangle. I slapped on more duct tape -- the window held together till we got home.

Of course, the glass is not covered by the extended warranty. I am pretty sure that I can safely remove the old window myself. A local auto glass shop told me to bring in the old window and they will cut me a piece to match, from a sheet of auto glass.

So that is my question -- is that the right stuff to use? Or maybe the glass they use in clear shower doors? I am not worried about the tint -- I can apply an after-market tint kit, which will be adequate.

Thanks in advance for your advice!!