I understand that you want to use time-lapse parking mode. My statement about motion was related to the criteria for the dash camera to switch from normal recording mode to parking mode. There's a 5-minute requirement for the vehicle and objects within the view of the dash camera to be motionless before this approach to entering parking mode will allow the dash camera to enter parking mode.
I've been trying to get clarification from VIOFO about entering parking mode when not powered by one of their hardwire kits and it's been a bit mixed in the definition. They have stated you should use the VIOFO supplied USB cable and not a third party cable. The 5-minute period of no motion seems to involve what is visible within the field of view of the dash camera(s). It can take longer than 5-minutes if motion is detected within the field of view of the camera(s) or if the is an obvious light level change.
If it were me, I might still get the HK4 hardwire kit and create a wiring harness for the battery pack power source that allows the HK4 to get 12-volt power from the battery pack. The battery pack will of course provide constant power, but you can simulate ACC power by having one wire from the battery pack's 12V power connect to the HK4's battery wire, another wire from the battery pack's 12V power would have a SPST switch which will let you simulate ACC power. When you plug the HK4 into the battery pack's 12V power port (with this custom cable), you'll have the ACC+ switch "On". Let the dash camera boot and after it starts recording in normal mode, turn off the SPST switch for the ACC power in that cable and the dash camera will enter parking mode immediately. I've had to create a few of those 12-volt to hardwire cable/kit cables with a switch to simulate the ACC power to power the dash cameras in my filming studio with a 12V AC-to-DC power supply.