Having LARGE, somewhat-fragile things shipped is always a problem, and I wish you well.
I bought a pair of Vandersteen Model 7 Mk.IIs that were cartonless in New Jersey last year and ended up flying there wiht my daughter, renting an CUV, wrapping and loading each into the vehicle, adding the crated poweramps, and driving all that 2500 miles to Phoenix.. This is not a suggestion that you do this, only an obvservation that we audiofools sometimes go to great lengths to achieve what we want.
Have you checked with a furniture mover? One might be able to wrap them in enough furniture pads to transport them unscathed.
In any event, I wish you success.