A good evening in the shed tonight!

I'd been having difficulty sourcing a suitable piano hinge for the trim tab.  While the Zenith one is entirely reasonable at about $21, it would have cost $108 for postage to Australia.

Finally tracked one down locally today - it's stainless steel instead of aluminium, but because of the thickness (about 0.025") it's light enough for the purpose.  I intend to well and truly coat it with an anti-corrosive paint to avoid any corrosion problems where it meets the aluminium.

I cut it to size (935mm - although it's inset into the elevator as per 750, it's going on a 701 so the elevator is shorter) and drilled it to the trim tab side as per photos.  Couldn't be happier with the result, it moves freely and when clamped to the trim tab spar, meets nicely at the bottom at full deflection (not that it will ever get that far!)

I'd previously coated joint areas of the elevator skeleton with primer, so fitted everything back together and clecoed it all.  Very happy with the evening's work!