I also feel compelled to warn you: Strategus is nearly impossible to play as a single player, so in many ways it's not like single player Warband at all. Trade routes are coveted, especially on NA side. This makes raising the finances for an army very challenging, as trade is the fastest way to make money. In fact, you can only raise enough money for 5 decently armed an armored troops per WEEK without trading. In a game where armies are usually around 200 in size, this makes it impossible to finance a fight without trade.
I'm not saying it can't be done, but you just can't avoid the reality- you have to work with the factions (all player run) to survive, especially now that so many borders are being locked to traders.
In my opinion, if you're limited to working with the factions, you might as well join one. Thomas Hobbes had it right, the natural (Strategus) life is "solitary, poor, nasty, brutish, and short."
As an added benefit, your new clan mates can also teach you more about the finer details of Strategus.
Welcome to Calradia.