Ozrunner replied:

and the notes don't say that. Read the trek notes again.

You enter from Callcup Hill and exit via Yeagarup dunes, ie in a loop.

The Explorer replied:

Hello - The trek actually passes over the Callcup Dunes and not directly over any one specific hill. The highest point of the dunes in this general area is referred to as Callcup Hill. While you don’t actually drive directly over the top of Callcup Hill the trek takes you within 300 meters of it (and you can as you say take a detour to the top). Where this hill stops and starts is difficult to say as the Callcup Dunes are a convoluted arrangement of many crests and hollows.

AFAIK there is no hill officially called Warren Hill in the area, though maybe that’s what the locals call one of the many hills on the actual dunes (there are many hundreds). None of the maps I have show any hill called Warren Hill. The track up from the beach is probably best referred to as ascending /descending the Callcup Dunes and not any one specific hill...though Callcup Hill is not a bad choice as it is the only one marked on maps and the track arguably goes up and along at least the side of it.

Cheers
Greg