Mike,
You have a lot of control in a lot of different ways. If you're going for an exposed through end you can mill the thickness and width to be a very snug fit, then use a hand scraper or block plane to shave a little off all but the last half inch or so. You can take a carving tool and make a few small grooves along the length from a half inch back to the internal end. When I did my coffee table with padauk slat shelf and padauk through floating tenons, I did both scraping and grooving. And of course, if you're using the bits to make larger tenons that will be blind, you can always make them a tiny bit thinner and a tiny bit narrower.