I do not have the game and never played it (would love to play it) but I think I might have found something. Look at these stages, they might be broken down quickly. Satonda Island's and Mount Kenya's start and finish lines are right behind each other!!! Try it out!!!!

Dune did in fact think of that, if you go even a little backwards beyond the starting line then it resets you right away.

Oh no, maybe there is a window to get pass the triggers

https://www.speedrun.com/posts/cqjp8

All of the stages seem to have certain triggers around the actual road which they reset you on, but it may be possible (doubt it). I know there's a mod where these areas are visualised for time attack practice purposes, but could be a fun investigation if it's not already been done :)

I did have a look at it briefly, there are no red hard reset bubbles behind the starting lines on these tracks and in fact there's still white bubbles denoting the road is valid, but you still get reset. There must be something else going on as you can go backwards as much as you want once you're on the stage but as soon as you go backwards cross the start line it'll reset you.

IIRC, the game uses reset zones and bubbles, but also invisible checkpoints (skip one and you get reset), so large skips like this likely aren't possible.