yes, if you mention in your statement of facts that you were traveling above 65mph (or 70mph in areas subject to VC22356b), you can be found guilty even without the officer's declaration.

Also, unlike prima facie limits governed by VC22350, 65 and 70 are MAXIMUM speed limits that may not be legally exceeded for any reason unless you have a gun, a badge, and you are driving with lights and siren. So, the prevailing traffic speed and conditions will not work as a defense.