I've come to sing the praises of small ships!
I have a couple several thousand P ship designs, two versions of a battlecruiser, one at aroun 4500 (maybe a bit more), and another at around 5750 (which has a station shield emitter and missiles). But I've been playing a 118P ship and just wrecking with it

It has a factory, several containers, some thrusters, and two of the triangular point defense cannons... I also have a bevy of < 500p ship designs, most < 200 to go with it, it can also make the next size class factory ship up, which can make my station, which can make anything, so if one of these survives, it can rebuild the entire empire!
Not sure if the agent AI will snowball this fleet correctly, but it's designed to be a nuisance in other people's games
