Why not just use 24V power door lock actuators? I found those (both 2-wire and 5-wire) on e-place for $10 a kit (one per door) doing a simple search for
24V Power Door Lock Actuator Truck (linked here). You can also find 24V code-hopping remote control kits for less than $50 there, another simple search term of
24V Rolling Code Remote Control. I'd stay away from the cheaper RC-hobby RF stuff, since it's not secure at all - might as well leave the keys attached to the outside handle... and in general I'd recommend that you avoid kludging a lock together. Think of it like encryption - if you are just doing it as a hobby, you probably don't know enough about encryption in general to think of all the holes you put in ("hard" for you is not necessarily "hard" for everyone).
I'd recommend staying away from electric deadbolt locks meant for buildings, unless you do something like an
electric mortise lockset. These are normally 24VAC with a rectifier for commercial building access control, but you can do DC too direct - just pair it with one of the above linked search RF kits and your truck's batteries.
Electric deadbolts come in two flavors, fail safe (unpowered=unlocked), and fail secure (unpowered=locked). Obviously running fail safe, would mean that you need to power a 5Amp solenoid continuously so it would run your battery down (then it would unlock when the battery dies - so you can't go anywhere and your stuff is all gone). Running a fail-secure deadbolt would require you to power it to unlock - but that is a safety issue, since in a crash your power wires might get cut and you might get trapped in there (think roll-over or something).
Mortise locksets are ADA compliant (easy to operate), have "settings" which allow you to make the inside handle always operate the door for egress, or require you to manually use the inside knob to first unlock the door, then exit. The momentary solenoid (fail-safe) would allow you to connect the outside handle to the operator mechanism on "pulse", or you could use a key to manually override the lock. They also fit entirely inside the thickness of a door - I think this is exactly what you're imagining.