I was thinking overlapping, not in the intermeshed//same plane over lap, but the rear pair mounted higher that the front pair, like how a CH46/47 have the rear rotor mounted higher, maybe the hole rear wing or engine mount could be built the same way? Or does that still reqr synch?
I've been giving this some thought, if the rear rotors are set higher than the fronts there will be problems when the nacelles are turned into airplane mode, the prop circles will collide as the rotors of the rear engines turn down and the front ones turn up, the two arcs will intersect. However, if the 'front' rotor is set higher, this doesn't happen ---