Yeah, I agree with the dynamic AI Income.
Though it seems an easy solution, it would be a quick one to implement if developed in a good way.
Follow me in this one.
Just put the AI income at high rates, maybe with a constant that a player can choose. Then let the AI produce a lot of ships instead of just acting like a normal player.
If you want more, just let the AI build quicker, research faster and so on.
It's an easy solution and has nothing to do with complex tactics or designing a super clever AI, but trying to beat an enemy that grows as fast as you do, that can build faster than you do and all the previous said things, should compensate the lack of tactics with a superior firepower. But, as an easy solution, it's another very challenging AI which you can adjust to meet your needs.
Maybe I'm saying the obvious, but, who knows. From an ignorant programming point of view, it seems a matter of only changing some variables and tell the ai to go for the strongest ships and to push research hardcore, as its research rate is multiplied anyway. Should be a doable task, no?
Btw I saw some guy messing with Cheat Engine on star ruler and they managed to catch the enemy AI variables even of ships and such and you might end up in being able to make AI stronger than it is now. If someone is interested and if I can link that kind of things, I can show you where to get that (though I won't use it for a long time, as I just bought the game and still don't know how to play).