8kph would work out to around 4.3 kts (nautical miles). You should have plenty of steerage at no wake speeds. Bow wonder is a natural phenomenon and is curbed by getting used to not over steering.
To hold a straight line; once the boat starts to wander left, you turn right. Once the boat starts to respond by turning right, straighten the wheel. Basically, turn until the boat starts to turn, then straighten again. You'll find you're almost wagging the wheel left right over and over and going straight.
If you turn until you're aimed in the direction you want to go, then straighten, you'll continue the turn well past your desired heading.
A smaller prop for no wake speeds won't fix that. Only handling will.