Well, in GT2 it had a supposed 2.6 miles and could be done well under two minutes, while the real stuff has 12.5 miles is just shy of 8 minutes.
So is pretty safe to say that it isn't a exact copy of the real one.
Nowadays the hardware has the capability to manage the whole extent of the course, so no reason to not have it.
Don't know what direction PD is going, as a time trial stage could be of less use on Sport Mode, so not such a priority, but with 12.5 miles still could be raceable with multiple cars, from start to finish (12.5 miles is about the same as 18 laps in Catalunya Rallycross Layout), Sega Rally style, so to say.