I'd look at finding a used bike. Make sure you find a bike with long chainstays and braze-ons for racks. A real low gear for climbing really helps - usually that means a front triple. If you will be hauling a lot of gear or unusually shaped items, you may want to consider pulling a trailer.

An older mountain bike that had quality components for it's time might fit your needs. Make sure the frame is the right size and that everything is in good working order. Switch over to a tire suitable for touring, buy a trailer and go out a enjoy yourself!