Would it be a good idea to make the 'Scrap consumed per damage dealt' function to be toggleable under each individual protection level?

I agree with that idea! Infact I have been working on the next update, and you will be able to modify every cost setting per Protection Level.

Stay tuned!

Merged post

As of v2.0.0, you can now configure the 'Structure damage cost` independently for each protection level. If you don't specify this, it will default to whatever value is present for `Default structure damage cost` in the Cost settings part of the configuration!