you need a couple flush/template bits;
i would suggest the 1/2"-3/4" wide bits x 3/4"-1 1/4" long
that should get you thru most routing applications with a template;
stewmac sells a a 3/8 finishing template bit to get the corners tight, i got one, but i dont use it ; its still not tight enough for most soapbars and bass pickups;
i use a standard 1/4" bit with its shaft as the bearing against the template;
do your intitial route and then carefully go around the corners with the 1/4"
hope i explained that good