Here's a mod# 10 clear utility lamp that mounts just like the large rounds. It's a 2 1/2" lamp, but you'll have to cut a hole about 2 3/4" to mount the grommet & the grommet will actually cover a 3 1/4" diameter surface. This is the closest I could find that fits what you're looking for.
Matt
mod# 10 Trucklite
Mounting Grommet