Get a large 26800mAh power bank, now down to about $60.

I have two power banks. One battery for the front camera and one for the rear camera. Leave the cameras running all night. That way you don't have to trust the camera's G-sensor. The downside is if your car is damaged you will have to search a lot of videos.

Buy high-endurance memory card with the largest capacity possible. Currently, I'm using 128GB Samsung high-endurance cards. About $33.