Scott,
Provide method of securing empty fuselage and wing dollies so they won't roll around in an empty trailer during a retrieve.

Someone else mentioned spare tire, but make it easy to get the spare tire out and the flat tire back into the trailer. My spare is located under the trailer behind the axle. It's "okay" to remove, but a real tough chore to remount. The 15" steel rim and tire are HEAVY. I've thought about making the "hoist" type of arrangement that some pickup trucks have for their spares.

Don't skimp on the size of the front cargo door. The newer Cobras have large doors. Older trailers have smaller doors. Go big!

Ray