Would anybody know a supplier of nice neat light pop up tie-downs that could
be used to replace the Lancair supplied screw in ring?

I suggest  you contact Campion Boats. They use some very elegant pop up "tie downs" on their sport boats. The model installed in boats might be a little heavy for a Lancair, but I am sure they come in various sizes if you find out who manufactures / sells them.

Best regards
Tim Jorgensen
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