Drill a hole next to the keyhole and slightly up. Then you can just stick a screw driver in there and push the latch to release the trunk. I have done this on a few cars in the junk yard.

An emergency pull cable routed to the inside of the cabin is a good idea.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge