65 Ammeter now shows overcharge when accelerated

If the ammeter settled back to near 0 after 30 minutes of running (idling?), then that sounds pretty normal for what was a fairly heavily discharged battery being charged up by the charging system. If you drive it for a while rather than just idling like you did, the charging system will put out more voltage than at idling, and it should go through another cycle of showing moderate to heavy charge and then settling back towards 0 as you drive more and more. Measure the battery voltage after a drive of 30 minutes and then resting as described and see if the battery is now closer to 12.6 v after resting. If that all works out, you have a good battery and charging system and no need to carry an extra battery.....why guess when you can test and know?

As for the headlights and the bezel, I would first suspect that you have a loose taillight circuit connection at the headlight switch and it got moved and made a connection when you tightened the bezel. The bezel does not ground anything not does it have anything to do with the taillights.