go to the Mission menu, and in Parameters check "Ignore Player Units"
That appears to be the key to the whole thing, with that checked on it ignores any errors and just saves it.
That's what I got so far for the secret Luzon Straits resupply base, added a couple of shore batteries to defend it - the Marines have landed.
To do list;
1. Figure out where the trees and bushes are, add camouflage to the tender - something like that you would normally have a steep shore with deep enough water close to the edge with netting and brush, that could be faked with just a small strip of land with a line of palm trees, or trees set on the masts.
2. After testing figure out how to package and upload the little beast for those who are interested.
That's what it looks like after the fall of Java, instead of shifting to Australia and having to go 2000 miles just to get to where the fun is, the new base is closer to the action and resupply is only 1500 miles from Tokyo.