truth is life 说:
You can actually go it alone, since you by yourself on a horse are faster than most bandits (especially once you get a couple of extra pack horses). Just stay away from Khergit and Sarranid territory, except the fringes (Halmar, Narra, and Shariz), the desert and steppe bandits are numerous and tough without a fairly decent force.
You seem to have no experience in dedicated trading. Try loading up a full inventory of Iron Bars and then see how fast you go on your own. You'll be a snail, and a good target for bandits. Even though you compensate it a bit with 6-9 horses in your inventory, if you do dedicated trading you will want to use Ctrl+Space to speed it up, or else it takes ages. And with Ctrl+Space you don't have the time to react to avoid bandits. 10-20 Mercenary Cavalry can crush almost all bandit parties unless they gang up, so just be careful near the places where their lairs usually are. The money lost on their wages is easily earned back by you travelling safely.
When I start a new game, I keep trading until I earned about 130.000 denars for enterprises, and about 300.000 denars for equipping myself and my companions with the best armour, weapons and horses in the game. That's between 400-500K denars, and it takes me about 250 ingame days to reach that point. It's about 80% of the preparation required to kick ass in Calradia, the other 20% being the power levelling of myself and my companions on bandits, so they get to level 20 and have the right party skills + all of them Trainer. I'm then set to go and do anything I want, with success. My enterprises keep me filthy rich, and I can stamp an elite army ouf of the ground within a week due to my trainer companions. Plus me and my companions are the most elite and immortal champions in Calradia.