Has Nigel got a new Stealth?
As for double stacking, I have put an A Class directly on top of the Stealth before now with the Stealth sitting on the normal trailer cups. When Paul and I went to Zandvoort last year he customised his trailer so both were independent of each other. This year John A took two Stealths back from Mumbles with him, he used an old tyre on each beam corner and ratchet strapped everything. I think it worked!
As long as the trailer is in good shape, the cups are well padded and you can avoid the mast foots and travellers causing damage you should be fine (famous last words)


Don't forget a means of attaching the masts and put your beer in an accessible place!