"Combat" implies military pilots flying under military rules, outside of FAA purview.
Vintage warbirds are flown under FAA rules called FARs. Federal Aviation Regulations.
One of these rules does not allow initiating flight with an aircraft that is not fully airworthy.
A violation of a FAR can result in the suspension or revocation of your pilots license.
Cost or convenience of repair to airworthy, does not suspend any FAR.
If you can do it, you can fly an unairworthy aircraft to a landing site of your choice. But, there it will sit until repaired to airworthy status.
Cheers,