I doubt a dashcam's draw would create issue after 12 hours; however you may greeted upon return from a two week holiday with a problem that costs more than the dashcam to resolve. Our '12 Chevy Astro ate a battery every two years until I realized my young son who traditionally sat behind me habitually left on his eyeball reading lamp.
Auto batteries provide a large current for short duration and today they design using "eye-droppers". When an auto battery is exhausted of charge, it can become fatally damaged. I've had batteries come back after a complete discharge, but rarely after a second.
The beauty of using an add-a-fuse connector is you can change your mind on what circuit to use without rewiring.
Our '06 Trailblazer and '12 Malibu have battery run-down protection which de energizes stuff left on when the voltage drops to a specific value. Sharing an always-on circuit downstream of this protection could be an option.
Many 12V sealed lead-acid batteries power UPS and similar rechargeable devices and replacement batteries in many dimensions and capacities are available on Amazon and similar online retailers at reasonable prices. Wiring such a battery with diodes to a circuit energized with ignition and powering the dashcam from the battery is another option. The car charges the additional battery and the diodes prevent the car from draining the additional battery,which powers the dashcam without drawing vehicle power when the engine is not running.
Hope this helps, good luck and keep us posted