The easiest way to accomplish this would be with a 5spd freewheel. I bought a 29er wheelset that is threaded for a 5/6/7spd freewheel. I intend to use 6spd, but you could put a 5spd on it. A friction shifter would keep you from having to exactly match speeds between shifter/derailleur. A bar end OR downtube shifter should work.

BTW 29er is the term for wider rimmed 700c wheels used on MTB's. Lets you choose tires from about 28 to 35 depending on frame/fork clearances. Brakes are determined by frame type--road bikes are usually calipers, cross and MTB's are canti/V brake. Some are set up for discs.