G-10 tips from an enthusiastic amateur:

The easiest way to get G10 in sheet, rod, or tube is from McMaster-Carr (www.mcmaster.com). Flame-retardant G10 is sometimes cheaper than regular--either will do fine. In large quantities, other suppliers will be cheaper, but nobody beats McMaster for nearly instant delivery of everything they have in the catalog.

I scuff sand any G10 that will be bonded, though the tube probably doesn't require it.

I cut G10 tube with a dremel w/ cut-off wheel; hacksaw can work. It will dull your bandsaw blades...

Often I drill up from the bottom of the deck with a forstner bit for the G10, leaving original deck laminate at the top and push the G10 up into the hole from inside. This way the upper skin caps the tube and there is even less chance for water to get to the core.

don't be afraid to wobble the drill bit a little to make room for the vinylester. Also, be sure to coat both surfaces before assembly.

I cut the G10 a little long and grind it off after assembly and cure (die grinder is best).

Fasteners through holes with G10 tubes that develop leaks will be readily apparent, as your fasteners will leak/rust inside. Traditional installation with sealant often hides leaks because it soaks into the core rather than drip below.