R.I.P. Sorry for your loss... you work half a lifetime to get some thing and some clown takes it away (or just destroys it) in a few minutes.
How long does it take to disconnect the battery? Keep a shorty ratchet and socket on hand, take the extra 30 seconds to disconnect the battery before you leave your vehicle. Take the ratchet with you, it shouldn't be hard to hide it in a pocket (or purse, if you're of the female variety).
Sure, it might be inconvenient to reset the clock afterward, but the extra 10 seconds it takes to do that should be more than worth it to save you the cost of a new vehicle. And the clock can wait until you're out of the sketchy places. Your phone has a clock.
Rigging a kill switch is also easy, but that can void warranties, ye be warned.
If you don't want to pull the battery every single time or rig a kill switch, you can just pull your starter relay or your fuel pump fuse or some other such. Of course, a truly dedicated baddie could still work around any of these things, but it would make his job harder.
If the OP's avatar is the truck in question, there would be more - much, much more - involved than just resetting the clock every time he disconnected the battery before going to sleep at night or walked into the office for work every day. Presuming, of course, that he's not in the trades and doesn't need his truck for work.
Reset clock, reset presets, computer starts from scratch relearning, lose mpg calculations, no remote start, no auto unlock...
At some point, opening and closing the hood everywhere you went, connecting and disconnecting the battery, someone is going to see that and just do what they saw you do. By the way, the door lock is electric and the hood release is inside the truck so you either have to leave your truck completely unlocked all night or use your key manually. Could do that but it kinda sucks for remote start on those cold snowy mornings.
Fuses and relays, similar.
It's mostly dedicated baddies getting these trucks now as it is. Better off just adding "The Club" as another layer of security and hoping they dont just flatbed tow it off to some impromptu chop shop.
These days, most of the youngest two generations that are able to drive are unable to drive standard shift/manual. You could get a manual shift, write instructions how to drive it in cursive handwriting, place those instructions on the dash, and STILL not have to worry your car getting stolen by most 20- somethings. Cursive handwriting is like secret code or encryption to some of these kids, and they see driving manual as akin to churning butter or crank starting a car.