Another thing you could try is if you have someone you know that owns a delorean close by, longshot i know but i have seen it before on older cars where a key from another car can unlock strangely only one of the doors so try both,, wont do ignition barrell tho but you dont need that ofcourse you just need in.
Another thing do you have breakdown cover, may sound mad as you have had 3 locksmiths out but in the uk we have the AA rac and others, they are usually quite good at getting in, they call the office and at some point someone nationwide will have been locked out of a delorean so the breakdown mechanic will log it at HQ what they did or how they got in to help the next poor sod.
Good luck... xmas eve aswell mad..