I read this a while back and thought it was a great idea but I've only just got around to trying it out. I'd never played for a 20K game at Deity before this attempt and it worked out well. Sorry to bump an old thread but I thought that you might be interested in a few details so here they are.
I decided to play a Small map with the Byzantines for the SGL opportunities and set up with a couple of Rel civs, hoping for an early trade for CB.
The start I picked looked pretty good...
...but when I moved the settler off the cow, I just had to move it again as it led to the Holy Grail of 20K starts. 2 cows, a few hills and bgs but most of all
only 2 coastal tiles. I later found that I'd also brought an iron hill into my capital radius.
I then explored a bit with a couple of warriors and saw that happiness was not going to be a major problem.
The only issue was a lack of food/workable tiles outside the capital and so I took the unusual step of getting three settlers out before going for the Colossus. This did hamper early culture somewhat but I decided that my research would benefit in the long run and that would bring in the SGLs.
I had the island to myself...
...but as usual on the higher levels it's a case of whether you can claim it before the AI gets to Map Making. I almost managed it but the AI did get a couple of towns. It helped that there was a massive amount of marshland, so I could clear it and the settle when I had the worker time.
In the meantime my goal was the Republic slingshot and the technical domination. I managed this and used the MoM to kick off my GA. After that the AIs were trailing in my wake. I traded my luxes which kept them happy and every 20 turns I traded a tech which helped my research and made them ven happier.
There was an awful lot of marsh and jungle to clear but I finally got it sorted around 600AD.
Shortly after this I got a flip. This doesn't happen too often in my Deity games.
However I didn't get it all my own way.
NO SGLs! I was the first to get to numerous techs. 44 to be precise (not including techs from ToE and new era freebies). 44 techs and no SGL.

I can't remember playing out a HoF 20K game before without a single GL. (Did my computer know that this was my dream start and do this deliberately to spite me?)
Limited resources. I found that I had two sources of iron early on but no horses. I can live with that but the only other resource I got was a single source of coal. All that marshland and jungle. I was really hoping for rubber and/or oil to do a bit of late IA warring for MGL farming but no such luck. Still at least I did have iron and coal so I could get those rails laid without having to gift the AIs up in tech.
A list of culture builds:
In the end I managed a finish in 1705AD-enough to beat the current #1 spot for this map size but with a bit of SGL luck it could have been so much better. If I try again, I think that I'll not have religious civs and maybe try for an earlier temple.
Thanks for this guide, sanabas.

You've helped me gain my first 20K victory on Deity.