Welcome to the forum Gbows.
The cameras that support parking guard ( pretty much all of them ) the corresponding hard wire kit always have a low voltage cut off, and here you should not go below 12.2 volts which they say is a 50% depleted lead acid battery, still that should not have a too adverse effect on your car battery, though it will of course last shorter than if you did not do stuff like this.
Anyways you should still be able to start your car with a low voltage cut off like that.
Next thing is dings as you say, this is a problem cuz often the ding are not enough to set off the G sensor to create a event recording, so to sneak by this you can as i do use low bitrate always recording, then your system record all the time and you miss nothing, but thats still a problem cuz then you have no chance of telling when you got dented.
So say you have been at the cinema, and after that a bit of food with the family, then lets say your car have been parked for 3 hours, then upon getting back to your car, and you actually see there is a new dent, well as there are nothing to highlight it you pretty much have to sit and filter thru those 3 hours of recordings and listen for the dent,,,,,, cuz low bitrate do have audio too, something time lapse do not have.
Anyway chance are it probably happned as someone came or left the parking bay beside you, so you can scrub fast thru your footage and just go 1:1 speed for when someone cone or go,,,,, but it is probably still going to take its sweet time to find the actual event.
So even that approach is flawed, but IMO it is still the best and you can often pair it with the G-sensor too to at least trigger on larger than ding events.
I am asking makers for even more sensitive G sensors for when parked in a attempt to at least have a chance against low life's like that, maybe even a keying event.
Also if you just have 2 cameras ( front & rear ) you will also only see the offender coming or going, there is precious few dashcams out there that have side cameras that give you a down the side of the car footage, like you for instance see from tesla cars.
You can then install a #2 system using the 2 cameras on a side window ( like i also have but not in use for parking ) but then you film strait out the wside of your camera, but people / deeds up real close to the car you dont get a direct view to, as the dashcams are not that wide angle, so my setup are pretty much only good for when driving, hence why i do not use the 2 side cameras when i am parked.
My 4 cameras in action, me walking around car.
A chance event i pulled from the side system of a car parking next to me ( 1 bay over )
side system recording oncoming cars in good weather ( slowed down ), at highway speeds ( which in Denmark is 80 kmh / 50 mph )
The Korean ( the sane Korea ) brand Gnet, do actually make a down the side dual channel system, but it is just 720p cameras, and not really something you can find much real life feedback on.
gnetsystem.com.my