Hi! I'm happy that you liked my feedback! here to help! =)
I agree about the new drive presets/difficulty. Slippy drift feels like a good balence for players to understand the mechanics and enjoy playing since the beginning. And them you can make it more difficult as the player progresses.
About the boosters, since you plan in making them a part of the world, and not just a power up, I don't think you need to add a minimum distance between them. The number of boosters and where they are in the road can be attached to the road modifiers you mentioned.
Eager to play it again when the new update launches!
again, congrats on the game! cheers!