The races are a massive pain but they're doable legitimately without using another player. There's several youtube videos with suggestions and I'd say pick one that seems to make sense, and then be prepared to run the routes A LOT to practice. I'm talking hours, potentially, especially if you're prone to panicking like me.
I'm still missing one of the achieves but the reward is an item with charges so I don't care about it - if that changes to a toy I'll be out there again.
Tip: to save on tokens you can start a race and then just spend time on the course practicing, instead of finishing (and then cancel the race buff aura to get back to the start point and start over).
The Hogs achieve is a bit of RNG but otherwise very doable without any sort of addon. It's just recognition and coordination. You want to focus on hitting Hoggers (3 pts) and not the regular guys (1 pt) and definitely not the babies! If nothing's up linger towards the center so you can rush over to the next Hogger(s) that pop up.