I would really encourage you to do the Tour de Cure. It's a great ride for a great cause. Don't be too afraid of distance as it isn't a race and there is plenty of time for rest stops and going at your own pace, especially in the mid-distances. Just FYI if the June 1 ride in the cities doesn't work for you there is a Tour de Cure in Fargo, ND, on June 15th. You couldn't ask for a flatter route. Last year the maximum grade was 3% and that was the overpass over I-29.