I haven't scripted in AGS in AGeS (it's literally been years). So a) I'm not sure I'm even using the right terminology and b) I'm not sure if what I was thinking was even possible but...
Basically you'd create a top-down view of the track (in Photoshop, Gimp, etc). It would contain all the stuff on the "ground". You import that into AGS as an object (each "track" would be it's own room?). You make the main background of the room a static image (the very back of the parallax scrolling that doesn't move... most likely just a color or gradient for the sky backdrop and other 'objects' would be the layers of parallax). You could then place other objects on the 'track' object that would be the sprites interpreted by the game (like pipes, sandtraps, power-ups, etc). Then, when run, all the objects would (through the aforementioned scripting wizardry) be handled pseudo-3D and you could cruise around the track!
I think creating the tracks/levels would be the easy part... we just need somebody willing to devote some time to figuring out the mechanics of the P3D!
If I have some time later today I'll whip up some example graphics for what I'm talking about. It's always easier to "show" rather than to explain