Looking good Mike. I’m sure you know that the color change doesn’t necessarily indicate flavor change, but the thermal cycling in the sun does improve the flavor extraction as the alcohol moves in and out of the wood with temperature swings drawing out the richness of the charred wood.
The amber color is produced by low concentration “color bodies” that are visible in the parts-per-million concentration but produce vivid color at low concentrations.
You might also consider opening the cap every few days to allow the volatiles to escape and be replaced with fresh O2 that enhances the oxidative process that enhances flavor. Kinda like what happens in a barrel as the “Angel’s Share” evaporates and is replaced with O2 mellowing the whiskey as it ages.