Thought I'd have a go at maxing out gold production and happiness.
It got a bit ruined at the start due to having to share my starting island and all of the resources being in their half, so an early war took me into the AD time-zone and drained most of my early gold gains, but the remaining few hundred turns were quite revealing.
For this roleplay/mechanics test, I built Temples until the town expanded, then sold them, then no other happy buildings. I built no Libraries and no further tech buildings. I only built Aqueducts, Harbours where actually needed to get to size 12. I built Granaries but then sold them when the town hit size 12. I built Courthouses everywhere apart from the capital. Everywhere had a Marketplace and any further gold multiplier building that doesn't generate pollution. I did build a couple of Culture buildings next to an AI city to prevent any flips and to secure resources. I secured Barracks everywhere with the Sun Tzu.
So after I secured Smith's Trading, my island only had Maintenance costs of 34 per turn.
For most of the game I set the Tech slider to 30% after learning Republic and Currency and was still able to outpace the AI until around the turn of the Industrial age, when one AI, Portugal, actually started outpacing me, forcing me to increase the slider to around 70% initially, then 100% as I closed in on the Modern Age.
Having the luxury slider at 30% without imported luxuries kept most people happy. As I increased the Tech slider I had to increase luxury trading to replace the luxury slider. I didn't build any Hospitals so as to maintain the ability to keep everyone happy. One town went to size 16 via Shakespeare.
I discovered that this playstyle is perfectly feasible on a Huge Regent Archipelago map and that Happy faces can and do build-up a good end-game score over the long term, and, for the 1st time, for me at least, the happy faces score even outpaced the landmass score:
I didn't have the patience to test this method in a military campaign, but it seemed good enough for that. I chose to ease out the game at Fission via the diplomatic victory condition, which, thankfully, I was patient enough to be successful at.