Hi Tim, welcome to the forum. Nice first post.
I do feel for you, been there, done that, had problems, grrr!
Sorry I cant help with the rack, may be worth a call to a recon company with your tale of woh!
They may be happy to give advice.
Have you had a look at the docs. in the vault
http://www.matrasport.dk/Cars/Espace/vault/J63/Would be a shame to have to buy a rack after all that work. Maybe you have a valve in the wrong place?
Best of luck.
Brian