I suggest decreasing the barbarian presence in Vanilla RFC in, at the very least, Africa.
The swarms of barb camels/horses/skirmishers and lack of independent Civs makes the Mali and Arabian UHV's nigh on impossible.
I almost finished Arabia only to have Egypt respawn right as swarms of Barb Camels swarmed in and razed an egyptian city I controlled.
With Mali, unless you get some free barb camel flips, I still deem their UHV completely impossible in Vanilla, though I've never accomplished it in BTS even still. I have literally lost on turn 2 with Mali because of the ridiculous barbarian presence in Africa. Even had two camel archers flip once and two horse archers and still could not keep the endless flow of barbarians at bay long enough to start building a couple elephants to turn the tide. One of my camels died attacking an archer with 100% combat odds (not a camel archer, not a horse archer, not even a longbowman...an archer...on a desert tile). Then 5 turns later lost all of my units and Timbuktu to an onslaught of Camel archers/skirmishers and spearmen from barbarian Egypt.
Unfortunately, I had to reinstall civ recently and have neither my Warlords or BTS discs
Please if you do any additional patching, take a hard look at Africa in Vanilla RFC.
EDIT: So i loaded up the Inca...yeah right. Within 20 turns of starting I had met the spanish with a workboat (no conquerers fortunately) yet with Plague lost 2 cities to barb axemen on the north coast of South America. Seriously, between barbarians and plague, vanilla RFC is almost unplayable it seems for many civs. 3 barbarian axemen could have literally wiped out my entire civilization if they had wanted to because of the plague. Three turns after the plague hit Venezuela, I had no more units in any city in all of South America. There was absolutely nothing that any player could do about it.
Guess I will try the Aztecs now, but from what I remember, they had any even harder time than the Inca with the barbarians.