So, it's supposed to take 4+ years to modify an aircraft that's already in production?
How long was it from the first -8 flight until Boeing modified it to be the demonstrator for the KC-135?
Dash 8 first flight--July 15th 1954, KC-135 first flight--August 31st, 1956..
(I'm sure you've heard of the -8s barrel roll during the hydroplane races, in August, 1955 -- I think the pilot came back over the race area and did another one! That kind of confident adventurism is evidently lost forever here.)
Hey, Boeing...Take an airframe from the production line and fit it out with the refueling gear and start testing!! Or, better yet, take one of your own 767s and use it!! (Don't tell me you don't have at least one (f)lying around).