I think that you're "allowed" to ride as far inside (well, probably not to the grass) as you are forced. Someone want to chime in with a definitive answer?

Oh, more questions...
When should the pace rider pull off? It doesn't seem to be the same point on the track each time, but sometimes just whenever someone rides up from behind and passes.

Is there a bonus for "winning" the second to last lap? Some guys will always spring like hell as soon as the pace rider pulls off, but I can't remember ever seeing one of these guys win a race. Of course they're going to get drafted and passed half a lap later.