SplinterGroup commented about 1 hour ago I like your thinking! a "V" bit might help. just cut deep enough to heavily score the veneer (but it'd be a pain to get the ID/OD accurate). Small bit may be good at high rpms, probably no top caul? maybe even masonite/thin mdf to avoid slivers and get fine dust instead.
I do plan to try without the caul. I think the main issue will be keeping the veneer from flapping around while being cut. My current plan is to cut a quadrant, tape over the cut portion, then cut the next quadrant, tape, etc. until I've cut all the way around.
What does the business end of that circle cutting tool look like? Is is a blade (like the tip of an X-Acto knife) or a small rotary blade?
It's a small rotary cutter, which was my main reason for choosing this particular tool. It's better at cutting clean and not tracking with the grain as a straight cutter tends to do.