I like merging two of the ideas here:
Damage timer increased if you successfully make it back to base.
AI flying the bombers back to base if you bail. They can still be intercepted to keep downtime from increasing, etc. If you re-up a bomber you are put back into your current flight (can get back to them to gun if you see they are intercepted). It still wouldn't stop people from lawn darting, but it could encourage them to let the AI return the bombers for them and still allow them to do other things.