Hell, I consider those tournaments easy. Even on low levels of everything. Archery/Throw skill doesn't count much, you will go for point blank, all my throw proficiency is from Torbah feast tournament spam. General rules.
1. Don't stop, when your horse dies, you die
2. AI is dumb, 1 VS 1 it switches to club and you can shoot
3. It is not about shooting, it is about riding- attack blind spot on enemy, keep behind them on their right
1 VS 1 if you are unlucky, to have enemy starting to throw all, you will have to circle until he is out of ammo (point 3. still applies, but AI will usually keep distance).