Hi Manuel.
Nice photo!
I am not into astrophotography, so I can't give any advice there.
And being from Sydney, I am not up to date on Perth dark sites...
But Welcome to IceInSpace
You may find more responses if you start a new thread with those questions (in the appropriate forums). Or do a search for dark sites Perth.
I know we have a few very helpful IIS'ers over there.
Clear Skies!