Good job, Mike.
I'm retired from the sea now but still keep my sextants (2) in use while on shore using artificial horizon. Adm Byrd used a box of mercury while in the arctic. IIRC, Lewis & Clark used mercury also & clearing the Lunar distance. Mercury is too hazardous and cost prohibitive these days. As a kid, long time ago, we used to take mercury from old thermometers and turn pennies silver with it. Yikes!
A dish/sauser of heavy oil works just fine in the lower, warmer, latitudes.
Davis Instruments has a plastic artificial horizon for sale that uses water as a reflector. Water is too viscous for my liking (jiggles with the slightest breeze even in those windproof boxes).
Cheers,