You could bevel it with your table or band saw before you attach it. or even ease it with a plane or sureform. No need to borrow tools when it will take very little work with hand tolls you already have. This of course assumes you've used a softer wood like pine for the shear clamp. I'd go for the router if I used purpleheart or a wood of similar hardness.

: I appreciate the responses. It sounds like it's common to do some relief, and
: the 1/4 inch router roundover sounds great. I'll have to look into this
: very soon. I rarely would have use for a router of my own. May be able to
: borrow. Either way, I can also see using the same roundover around inside
: of cockpit rim.