I've been searching the internet high and low for a new side glass for my topper (glasstite) and might as well be looking for a UFO part as common as these are (not)
Glasstite was acquired by BrandFX, so you could try asking them.
If that doesn't help then go to your local glazier or auto glass shop. Luckily it's just an oval pane of glass, not a UFO porthole.
We have went to a glass shop called Aladdin's and they said they couldn't do it because the window is curved
ahh well custom fit sure is a fly in the ointment.
You could try to hunt down a used top with the same glass.
Not sure if you can bend a piece of plexi with heat.
Otherwise, you might be S.O.L.
Pretty sure I'm S.O.L 😐
Are there any camper salvage yards in your area?
How about using a plexiglas rear window from a junked convertable?
You may find one close enough that you can trim to fit.
We have a Menards by is that has plexiglass.....