I haul quite a bit of music gear in my rides. My Galaxie is missing pieces of the trunk latch, lock cylinder, and bezel. What about a shaved trunk lock with an inside cable-release? I have an extra piece of trim to cover where the lock used to be (after welding up the hole obviously).
I am not sure if this would do the job for you, but I happen to know that a Honda Civic EX sedan of 1994 vintage has just such a mechanism. The pull handle mounts just to the left of the driver's seat on the floor, and it includes a cable release lever for a gas filler door as well. I suppose the latter could be adapted to another use of some sort, but that'd be up to you. You'd likely need a longer cable than the stock Honda one as Galaxies are a whole lot longer than Civics, but I expect that an appropriate one could be found with a bit of searching.
I was thinking of recessing the pull into the driver's door jamb... like Porsches have for the hood-release. Fewer bends, and tougher for thieves to notice. It's either that or full-electric.
Some '65 GM models use a pull cable with a T handle. Might be hard to find one, but it would work great.
I used a hood release cable for a early 80s chevy for a way to release my rumble seat lid on my 36 Ford it is mounted under back seat , easy to reach been in there since 1985
My '66 El Camino used one out of a Toyota for the access cover in the bed. The handle was mounted neaxt to the driver seat, but there is no reason it could not have been recesed in the jamb.
I'm thinking a little metal "cup" welded into the door jamb with a pull-handle in it. The cable would have a straight-shot into the trunk from there. I'll just reverse the latch (put the latch on the body instead of the lid).