How to handle the campaign AI on hard?

I've been playing through African campaigns on hard. Cleared Tariq and made it to sunny 4 but its very hard for me. I've made it this far but I feel like my playstyle is sloppy and often I dont really know what to do and just wing it so I wanted some advice if its ok.

On Sunny 4 the 3 AI rush you pretty fast. They send out a relentless assault of units and the map is too open to set up effective defenses. The best I've got so far is to either build some wall with a gap around my TC so enemies funnel into my starting TC which is garrisoned, then I just build 3 more TCs close to it and garrison those too as sort of impromptu castles that can pump out more vills. After that I was trying to gather all the nearby stone to line up some castles also while using a small number of longswords in the TCs to pop out and kill rams but then the trebs came and it was GG after that. Maybe if I had started spamming out knights instead of going for the castles I couldve countered them, but some enemies were trying to bypass the TC killzone and go for the walls to reach my eco so it was only a matter of time I guess.

In other campaigns I could only really manage by relocating to an area with fewer entry points e.g. in Sunny 2 I used the relic cart to take out the north enemy immediately and then built like 10 layers of walls around the single bridge entry point, I did something similiar in Joan 6 with the orange base.

I feel like there has to be a better way to do this. The AI doesnt play well clearly, they can be bated to attack TCs, towers and stone walls with archers, you can put a castle on their doorstep and theyll just suicide rush it, you can spam out knights and they'll never try to counter it with a pike/camel spam of their own. But I'm just falling to the sheer numbers they put out, constantly on the backfoot with my villagers garrisoned, my few free vills working on stone and wood, the few military units I manage to make get steamrolled and then they get behind my defenses and just massacre anyone who had been working and it's a slow grind downhill for me from there usually

I've seen Viper doing these and he's incredible, but even he seemed to be pressured heavily on Sunny 4, losing his ally base and his original TC and a lot of buildings, and having a ton of his units massacred, and I've not got even the tiniest slither of his skill and talent XD

So what are the super strats for hard campaign AI spanking?