Perhaps if you get several hundred signatures and present it to the Minister.
It's certainly not my call. Personally though I have no problem with us using the cycle path. It's in good condition, sparsely populated and guarantees no vehicular (motor - unless one of those idiot kids pops out on their dirt bike!) conflict.
Having a lunch stop at the start of the freeway section will mean the first riders are going to have to sit around waiting for a couple of hours! Although the idea on first glance looks appealing I don't see it being appealing to the vast majority. As it stands with all the rail works going on there wouldn't be enough cones left in Perth to cone off a lane the full length, add to that the lane detours and the surfacing in parts is not good for cycling.
You have to remember for the Great Perth Bike Ride when they coned off a lane on the Kwinana Fwy it was between Canning Hwy and Narrows Bridge. There were basically no on ramps between that short stretch. What you're proposing results in conflict with at least ten major interchange onramps. Traffic management would be one huge headache.
It's my own personal belief but I think the motorists would have had enough by that stage (after Asthma ride) and the inconvenience proposed here is at least 10 times worse. It's just too spaced out by that part of the ride and as such the adjacent cycle path is certainly more than adequate.