http://ridewithgps.com/routes/1989496 This gives us 50 miles - can do the first loop again for 67 - but gives us an opportunity at 2 maybe 3 places to cut it short. Only market is BoJack's at mile 20 - but could go on in to Eagleville for a market if needed around mile 32 or so.
So if you 18, 38, 50, or 67 - you can make this route work for you.