tdracer, Back in 2005, senior Boeing executives stated that '...the 787 is designed so close to the edge for efficiency that it could not be modified as a tanker'.
Modifying that fuselage to include a boom and probably some additional fuel tanks would, as you indicate, require a lot of redesign. Whether the highly flexible wing structure would cope with the plumbing and hardpoint requirements for wing AAR pods is another unknown.
But never say never....