Batteries by themselves typically last long enough, depending how long you run your camera. However, there is a problem with "ship" power such as those of us that record cockpit audio into a GoPro is that there is a terrible "hum" feedback which apparently is due to an insufficient ground? Not sure, but it's bad and therefore I cannot be plugged in while using this GoPro to record cockpit audio. I do have an external USB that CubCrafters installed per my request in the right wing root that goes to an inspection plate on the right wing via a stratus USB block I think is the brand, from which I plug in USB cable(s).
Also, in the process of going from GoPro 9's, 10's, and now 12's and also buying extra batteries, I have more batteries than I know what to do with. So swapping them out at fuel stops, or fly-in stops, etc. is yet another option.