If you are not going to replace the window with your own hands, I would take the trailer to the glass shop.
I replaced several windows on our Caravel
myself, and broke one putting it in, an easy thing to do. I think I measured a little too close, and the window was a little larger than it had to be, and one side was over the edge it is supposed to go into, and I broke it, so had to buy another.
If the guy at the glass company makes such an error, he will have to make it good, not you.