I use a dynamo rear light as main light that has about a 10min stand time, and a Secula Permanent on the seat stay that uses AAA batteries as a secondary. I use rechargable, but AAA batteries are available just about everywhere.
Also use the Garmin radar which also has a light.
Peter White once told me that mounting the lights in different vertical planes helps drivers determine the distance from them to you so that's how they are mounted.