Jim Conlin

Where can I get some of this mylar/scrim?

For anything but handrails, this sounds like overkill.

My last boat had about 75 lin. ft. of varnished mahogany toerail.  Each year, about 15% of it got scraped, sanded and 3-4 base coats, which took two days..  Then, the whole works got two coats more.  AFAIK, the toerails had never been removed from the boat.  

I saved the higher quality work for the cockpit.

I've built foils with G10 inlay in the trailing edge.  The building involves a table saw kerf (1/8") in the core blank, glue in the G-10 shape and sand the blank to reveal at least 3/8" of the G10 and apply sheathing.

They've held up pretty well.

When painting over gelcoat with a different color, every scrape reveals the lie.  

I'd think about painting it red or orange.  Have some fun.

Just seems like Aussie & Kiwi sailors are really keen on building & modding their own boats -- more than the average American sailor.  I have visions of you guys vacuum bagging your breakfast toast & infusing butter & jam across it.

Nah, I tried it.  The vacuum flattens the toast.  

Forget toast as a core material.