Herp a derp, forgot about the boost start in this game XD. Expect another WIP with all boost starts if you're interested in a full TAS of this game :P
What Version of Dolphin are you using? What settings? I am quite interested in seeing this happen.
Stock settings, but with Dual Core and Idle Skipping disabled so I don't run into any abnormal desync issues. EFB Copies is set to Texture so that shadows work properly. And I'm on 4.0-2299 btw. Only thing is that music is currently broken in this game, so that might make the TAS a bit boring until it's fixed :/