I have done a quick look-over now, and I must say I am not liking this idea for sending some GAMBIT invasion down south.
There are two southern continents, and what worries me is that they are connected to each other by at least 1 tile. Obviously, the 2 most advanced AI's will have that entire area railroaded over. Now look at their combined power. They will hit us with immense power. We are taking a relatively small invasion stack from our power, and shipping it all the way down there... and then hoping for the best?
It will take forever to re-supply that, and we will be losing units super fast, if not over-night. Even a little bit of seige by the AI will always hurt us. This just looks like a hope-ful gambit. It may work, and it may not.
When I look at the largest continent, it is true there will be more cities, etc. however the AI's are relatively backward. The Greeks for example, are still defending with a lot of longbows and cats even still! But more importantly, we can re-supply very fast, as we should. I suggest we land in 2 seperate stages. The first is the defensive wave. We land one great stack of pillbox specialists. And i's sole purpose is to hold a captured city and slaughter all the units the AI's will rush over. We got a great tech advantage on them now... as I said the Greeks are still sitting with catapults and a few cannons!
Our other follow-up waves will be CR tanks, etc. And we are going to get modern-armours soon which will lead to speedy city captures. I'd much rather use them there, against these three weak AI's, instead of shipping all the way down to big-bad-pappa (and his vassal), who is going to have a ton of perfect counter units ready to hit at a whim.
We don't NEED to go south at all. Everything we need, (pop and landmass) is right to the East of us. We only need to take over a specific percentage of that continent.
Please think on this some more...