I've a similar situation and suggest you look at running the ducts above the ceiling.
Major change, but better for the ducts and for maintenance.

We thought about this, but the major problem with this is that our
attic is small as well. The house was built without air conditioning in
1960, only a furnace. If we were to put the ducting in the attic, we
wouldn't be able to do anything up there.

-Nathan