I had a quick try at this, wanted to do no companions but it's annoying if you do get knocked out to lose all the skills, so ended up taking one with first aid.
Soloing went well enough did a lot of save scumming, shot a lot of bolts. Find it really hard to play the battles safely, I get impatient/cocky and start charging archers and getting my horse killed.
I got impatient and didn't solo for long enough, I suppose at this point is about when you'd gather companions and spend more time grinding bandits. As for skill points I put a lot in first aid before I realised it's useless if you're on your own, went for 0 spotting and 7 strength, sieges were hard/impossible with such a useless crossbow and poor proficiency (1 wm) and to few troops. Field battles however were a breeze with 50 Swadian Knights, I could have pretty much just left the room and still won the majority of battles. Although autocalc is predictably hilarious; I attacked 8 peasants with about 50 knights and 20 nord infantry and they managed to kill 3 knights and 5 huscarls???
Had a few ideas not sure if any of them are worthwhile; Sowing chaos and war to get the factions to weaken each other, you can do the make war quests and leave that faction join another and repeat or join the strongest faction and run around taking all the disputed towns/castles and leaving them weakly garrisoned. That wouldn't take that much time and should get everyone fighting nicely. Would probably have you be the most hated person in Calradia though.