Just remember they usually don't come slim because they have the contact depth for each side of the bulkhead equal to the diameter of the pipe for proper adhesion you can trim them back some but not much. Maybe a uniseal is more what you are looking for.
It’s to do my overflow so I don’t want them bigger than they need to be so if they crack or leak for some reason they can be removed without me having to remove the overflow.
Hayward makes a short shaft pvc bulkhead.
You can also call Flex PVC and ask them what they have.
They are pretty good at figuring out solutions to problems.
+1 in re FlexPVC. The person who runs the company is actually a fish guy, too, so he should be able to well understand what you're trying to accomplish.