If you know someone with an old set of late 50s door keys...I mean old, almost worn smooth...these will usually open a door with a little massaging from a file
I had a real locksmith make a set of keys for my dads car; he did it right out of his van in 10 minutes. He had a book that had the standard chevy profiles they used, and theres a number stamped on the key which somehow tells him how to stamp the profile on the key. He even had the old sombrero hat key blanks. I think it cost me $50 and a submarine sandwich.
Word to the wise, I did climb though the partition behind the rear seat backrest (I used to be 5' 10 and 140pds in high school) Its very dark, very cramped and by the time you go through what cobalt described, holding a maglite in your teeth...call the locksmith.
Can you call triple-A? I doubt they can pick a lock but worth a shot.
BTW that torsion bar that opens the trunklid? I was riding in the backseat when it broke and it sounded like a 12 gauge went off in the trunk.