Or there are some goodies inland of harvey, sort of in line with yarloop, at the back of nanga. But I'll have to show you them 1 day coz you'll get very lost before you find em by directions.
I could name numerous sand dunes or beaches but I rarely go as I find it boring & easy. Any decent 4x4 with simex's or BFG's at the right pressure with an experienced driver can do sand. I like climbing things that weren't meant to be climbed (not quite rock crawling). There are some good tracks at the back of bunbury, closer to brunswick junction but I've been there once so I'd need to organise my mate to show us.
I'm actually looking for new ground to pound too so maybe we could help each other there.
Serpentine has some good tracks that I'm familiar with. I don't know if they are still legally accessable but I could find out.