I'm not fully getting what you seem to wish to accomplish, but briefly; the real key as to what would work best centers on the setting and degree of control you will have in staging such a stunt.
When I did "Mind Blower" years ago, the gurney situation was nothing more than an asrah switch we did as the EMTs were covering my bloody corpse... I simply rolled out and under the drum kit stand with a folding Asrah gimmick set into place... when the EMTs "trip" and cause the vanish to happen, it really wasn't much more than flipping the thing around so the form hung on the back of the stretcher... very old thinking.
I can't help but think this same type of handling would be practical in the majority of cases but I would be amiss to not mention the old "fake assistant" method... one of the lads carrying the gurney is just a puppet (shell) into which the performer (to be vanished) simply steps into while the body is being covered...
I've used both and then some, but I think the moral of the story is, look up some of the older methods first, before you get too invested in physical gimmicks/tables, etc. Tarbell has a decent selection of ideas on this course.
In Addition to Alan's Points... I've done a few "surprise" bits with big escapes and effects, including the Water Cell, in which I not only employed the popular double-exchange ending, but we made the thing vanish... it was a one time only gig made possible by unique circumstances, in other words, it's not the sort of thing one can consider to be "practical"... to do it more than the one time removes the surprise factor -- the psychology such a bit demands.
Anyone that wants to do a big escape and place a magician's twist to it, doesn't understand what it means to be an escape artists. Escape work has little to nothing to do with MAGIC and being a "Magician". The psychology behind how it is presented, how one builds suspense, etc. is not even remotely close to what one finds in a Sub Trunk or even the Copperfield Death Saw type bit; both of which are ILLUSIONS.
If you invest the time and money to stage a decent escape bit, why ruin it by cheapening it and turning it into a magic trick? Why rob yourself of the media attention you will earn, when you do such bits on the legit basis and in a manner that does not smack of being a typical magician's PR gag?
It's really easy to make a great idea -- a stunt -- come off as cheap. The first trap being when we try to over-complicate it.
