Apart from the few USAF tankers fitted with wing pods, all the other options you describe facilitate on single receiver AAR. Refuelling a 4-ship with such a limited system, particular the nightmarish BDA, takes way too long - blindingly obvious to me. Ever tried prodding the BDA? I did so once using a Q-fit (8 missiles and 3 tanks) F-4 against a KC-135 without the benefit of any previous dual training and it was very difficult - as the Italian Air Force Tornado force discovered on Night One of GW1. During which the USN far preferred prodding against the VC-10K with multiple hoses than queuing up behind a USAF tanker - no doubt the letters of thanks are still with the squadron.
Much easier to let fuel flown downhill in an anhedral wing than it would be to pump it up the pronounced dihedral of an A340, given the pressure drop at such a distance from the centre tank - which would probably dictate a need for larger pumps and wider-bore pipes that are required for the A330MRTT . Following the demise of the Valiant, the multi-hose Victor had quite a long gestation period before it was a total a success - and that was with the urgent service need plus the design work of a major aerospace manufacturer rather than some independent contractor touting for profit
The TriStar pod programme foundered on cost and complexity- and in the end was deemed unnecessary due to the preference for modification of the VC10 C Mk 1. Because 'hoses in the sky' are perceived to be of greater importance than the total fuel volume available.
Have you actually studied the wing planform of an A340-233/300 outboard of the outer engines? Quite a narrow chord and winglet, with little structure available upon which to hang a pod pylon between the slats and ailerons or to provide sufficient pod clearance from the slats and ailerons.