Played some more. Mid game is probably the most difficult part with Patrians as the faction don't really have enough firepower to fight.
The Charger can be lackluster for a destroyer if you want some power and other destroyers are support ships. For the cruisers, the Lithuania is nice with its fortress shield, but while it is tanky, it lack the guns to stand against Dominators and other though ships, and it don't have frontal weapons. Pretty much the same thing with the Bastion, even though the large mount help a lot.
So a carrier fleet, even if it is crazy expensive to maintain, is definitely the way to go, since Patrians fighters are some of the best in the game.
That's it, until you can get your hand on the Yamato. That's the first and only powerhouse of the faction. You can throw it into slugfest against Onslaughts and win. I could almost say that the Yamato is overpowered. The Mayflower is a weird one. It has 7 large mounts but that's all, obviously it's a long range fire support ship but i didn't liked that much the Widebore used on it. First it cost 50 op, it produce a insane amount of flux, and the projectiles are very slow and not accurate, so not very good for sniping. The massive range and damage was super-efficient against giant Zorg ships though. But aside for fighting the flying death-boxes, i usually preferred to replace the Widebore with Gauss cannons, even if it waste a bit the ordnance points of the ships.
Overall, i think you should nerf a little bit the Yamato and buff the projectile speed of the Widebore. Also maybe switching at least one of the medium mounts to the front for the Lithuania cruiser. Other than this, everything is good.
And another thing. It is really difficult to attack Patrians fleets. Either you can fight the patrol fleet which is mid-game level, or the system defense one, which is end-game level. Would be cool if we had something in between to toy with, also some small scout fleets for early game.