Interesting! It seems that a drop-in florescent style LED tube is not a favorable solution.
The "Cabin Bright" product yields good results, but appears to be an installation challenge, and consumes more power than I hoped. If they were $10 a piece, I'd try one before a full investment. But at $32 ($43 for more light) a piece considering every fixture in the cabin, I can't see investing that kind of money.
I feel they should have used white insulated wire as not to see the wires through the translucent fixture when turned off.
An interesting comparison to florescent.
Here is the purchased product. (18" two bulb conversion example given)
Here is the installation.