Take a look at this thread guys: http://forums.civfanatics.com/showthread.php?t=205794
This may be the answer to all our "Too many units" problems. From what I can gather it is a patch that allows the maximum number of units to increase from a 2048 to 32,000, more than we could ever expect to reach! I have to go out now but I will test it out tonight. If anyone else wants to take a look as test it please do!