Let me throw a different idea out for high-sec:
• No structure requirements or requirements at all - other than the wardec’ing corporation needs to be in high-sec.
• All high-sec corporations have the option to opt-in or opt-out of wars (with the caveat that if you’re in a current way, you need to wait 24-48 hours to exit).
• Opting “in” gains that corporation a 50% loyalty point and 50% mining yield bonus (regardless of whether or not it’s at currently at war with anyone). If the attacked corporation owns at least one structure, their bonus is doubled, ie: 100% loyalty points and 100% mining yield.
• Opting “out” loses that corporation a 25% loyalty point and 25% mining yield bonus (so you can still be “safe”, but you’ll be earning less).
• NPC corporations automatically opt “out”, but lose a 50% loyalty point and 50% mining yield bonus.
• Bonuses are based on current values, so you’ll either be earning more (with more risk) or less (with less risk) with this change.
Addendum: Made a few tweaks with respect to NPC corporations and corporation structures.