If you can't ride outside now, at least stay on the wind trainer. You don't have to kill yourself, just gradually build up your endurance. I highly recommend building in a lot of time on the tour - much more time than you might actually need - so you can start slow, take rest days as needed (especially in the beginning), and play it by ear as far as your stamina goes. Plan to be flexible with your overnights - so you can stop when you are tired, and don't feel like you have to make that 60 mile ride to the next hotel you have reserved. It usually takes me into my third week before I feel I can conquer most things mother nature throws at me.