I have seen photos of US aircraft hanging a basket off the boom when required, wouldn't this allow much more flexiblity?
I'm not sure on flexibility for this fit. The FAF KC-135F and the USAF KC-135's use the hose and drogue fitted to the boom to refuel European and USN aircraft. However am i correct in saying that when this is fitted to the boom, the boom can no longer be used in flight to refuel the aircraft that utilise the boom to refuel, such as every USAF aircraft.
So in regards to flexibility, i don't think so. When fitted it can only refuel one type of option, the probe. It has to be removed to use the boom for the recepticle option.
When flying to support a coalition of aircraft using both types of refuelling options then the KC-135 can only be flexible if they use the boom and hose units on the wings... and not the type discussed above.