Good Luck Adam!
Unless you happen on a complete parts trailer, you'll probably have to either fix what you have or go with a plexiglass window.
My rear window is half glass half plexiglass - the previous owners removed all the windows
, resealed and reinstalled but 1 of the sliders in the back was cracked so they had to replace with thick plexiglass. It works perfectly, except none of my windows
open!! They're all sealed shut. I have a 'mystery leak' but it's not in that window, it's in the emergency window - somewhere in the exterior rubber gasket - I just can't find it. Yet it only leaks
ever-so-slightly when we have a driving hard rain beating on the non-door side (street side) of the trailer.