Welcome to the forum, @songline!
I too have (had?) trouble with my driveway and front yard for the number of recordings they can generate. You already did the first couple of things you need to do – that is restrict the Detection Zone to places where you DON’T expect traffic (but want to be alerted if there is some!), and reduce the sensitivity to get rid of spurious alerts.
On the passing headlights, you will likely find you need to restrict hours of operation for Motion Detection to daylight hours (not evening/dawn/night time). You can do that in Rules .
To compensate for turning off Motion Detection at night, we usually recommend use of a Sense Motion Sensor. That’s where it gets a little complicated. Version 1 of the motion sensor is no longer sold. However, if you have one, you are all set. Just put that where the camera looks, and when motion sensing is turned off for your camera at night the PIR sensor will pick up on anything warm walking by. You select your camera to document & alert any movement under Sensor Videos in the sensor’s settings.
There is a new V2 version of the sensor, but sales of that is currently being restricted to Home Monitoring subscribers. If you are one of those, you are all set. If not, hopefully that will change as production ramps up. For any motion or entry sensors to work you will need that $40 starter kit, as the sensor talks to a Hub, and the hub talks to your network.
To your question of can you use Cam Plus to force the V3 to only notify you (changed your words) if there is human movement, you can. If you go to the Account tab > Services > Cam Plus, you should see your V3 assigned to your license. If you then call that up, you first have to make sure Person Detection and any other options you want are selected. Then go to the V3’s settings > Notifications, and make sure Wyze AI Events is turned on. If you want people only, make sure All Other Motion Events is turned off.
The reason I had to change your wording is because you said “I’m wondering if there’s an option for the Cam 3 to ONLY record/upload an event when there’s human movement detected.” No there’s not. In the configuration above, you are only restricting Notifications (push alerts to your phone). That makes your phone much quieter, but any movement has to be evaluated to determine if a person is the source. So it is still uploaded to the cloud, and found under the Events tab for reference. You can let those lie, and they will go away in 14 days. Or you can delete them en masse by Selecting All, then unchecking which ones you want to keep, then Deleting the rest.
Hope that answers your questions. Since you are new and said “thanks team” I want to also be sure you understand this is a user-to-user forum and not a support site for Wyze. Wyze has a presence here, but not the support arm of Wyze. The best way to contact them is by phone at (206) 339-9646 Monday - Friday 5 am - 6 pm PT and Saturday 8 am - 4 pm PT. In the meantime, we users may attempt to answer some of your questions.