This mod will let you recruit any race units on debir.
http://forum.1cpublishing.eu/showthread.php?t=14769
It does provide a large amount of each unit so you would want to restrict yourself to keep the challenge up.
Maybe you can choose 5 types of units, no substitutes and you have to stick with them for the entire game.
If you suffer too many losses (say you are playing with low level units and no healers.) your forces just dwindle until you cannot win any more battles and lose.
The idea for the point based armies came from this thinking. having to use lower level units. but not all lower level units are as strong as each other. so I figured that you would want to rerate each unit to have a more effective level limit system.
So. this would make warriors very unpopular. That is why 3 versions of this all races mod need to be made with an appropriate variety and quantity of units to choose from. Seems a simple matter of decompiling the loc files with kbedit, changing the numbers of units in each ushop and recompiling it. the 2 mod files are nice and small.