Hehe sounds like youve been having fun, My advice in these frountline situations would be to have your best generals at hand. This way your army could have countered the advantage the AI had in this situation. Also, you need to make sure your army is composed of the correct infantry for this situation. I.e you will need A battle line of principies atleast 6, Supported by atleast 4 triarii along with archers and, enough cavalry to turn the tide in dire situations. Against oncoming full stack enemies, expecially when they are elite you need the best rome has to offer. In my view what i have just offered is the best to face the challenge. Good luck with your future campaign keep us updated :)