It is very difficult to avoid domination on a relatively small continent
While the game may be over, I have used an unorthodox method to get past this restriction for a HOF game. No, I'm not talking about increasing the Domination Land Limit using Colonies. Think a bit harder: there is a second condition that must be met for achieving a Domination Victory.
That's right, Domination Population percentage. In one game, where I had 3 widely-spread-out Legendary Cities on a Duel or Tiny map, I owned something like 85% of the Land Area (which even Colony shenanigans wouldn't help with, as Colonies can only get you up to 76%, at best) but was able to avoid triggering a Domination Victory by heavily whipping my Cities down to the Size 1 to 3 range. Once I had all of my Cathedrals built, I no longer needed the extra Cities for the total number of Temples to build Cathedrals in each Legendary City requirement, so I was able to give away my Non-Legendary Cities to the AIs and regrow the population of my Legendary Cities.
The key was to avoid completely destroying the AIs, so that they will have enough of the world's population under their control.
A far more consistently-applicable approach would be to locate your Legendary Cities physically close to each other, so that the Cultural radius of each City will overlap with that of the other Legendary Cities.
That, and don't spread Sid's Sushi to your Non-Legendary Cities unless those Cities aren't going to earn you many more squares when their Cultural Borders expand.
Pretty cool-looking map, though--as you say, it isn't what you'd normally expect to see from a Pangaea map.