How can my lower level commanders survive killing events?

They can shield for the weekend. They can unshield and be reinforced by stronger players (the reinforcer will get the points). But teach everyone to shield for the weekend (3 days, started at reset Friday), and avoid all kinds of issues.

Most states will organize a trade zone, or you can arrange trades between individuals. The weaker base keeps shields, and puts out troops on land or gather plots. The stronger base attacks those troops and everyone gets points.