Heheh, I can sense the hand of Gandalf in this game
Some comments:
1) Play EA -> MA -> LA. The computer will do worst in EA (high magic) and best in LA (good troops)
2) Consider the NI (No Independents) mod. I have heard SP players swear that it makes the AI far more functional since they do not uselessly spam garbage indies.
3) Give the computer premade pretenders - if you can, particularly give them non-crippling scales
4) Indies 3-4. Enough to make human players do *some* investment in indy forces, but not enough to confound the AI.
5) 1-3 Starting provs. Will prevent AI from crippling resource shortage w/ resource heavy nations
6) Step up resource multiple as you step up AI difficulty. You will be amazed at the armies it can build (however not feed, alas!)