As someone else pointed out, filling the hulls with water may really exceed your trailer's ability to keep it off the ground. Looking at where you have it, it looks relatively sheltered. Take off your clears, anything easily removable to reduce windage, and expect to have to clean the crap out afterwards. Leave any bungs out or scuppers open. If you can, sure, put in some star picketds and tie-down ropes, don't overthink it. You do realise that the greatest risk to your boat, should you get Cat 3 or more, will likely come from other people's flying debris? All the prep in the world. apart from actually putting it inside a cyclone-rated shed, won't help when someone's roof slices through it.

I know all this from experience, both from having lived in WA for for almost fifty years, and from being through a few personally. We went through Cyclone Seroja in April 2021. All the wind gauges broke, estimate of peak winds was in excess of 240km/hr. Forget about being in the path of the eye, we were just offset, which is far worse. Your most destructive quadrant is just inside the eye wall, on the south east corner, and we got it. BOM radar image I screen shot as it approached--direction of approach was NNW, probably slightly more west than north. Houses were unroofed, smashed completely in some cases, so much damage done from flying debris. Most street running east-west had their power lines ripped down/poles snapped off from, again, flying debris.


Our house came through it OK. Houses all around us were unroofed, some were eventually repaired, others had to be demolished. You soon find out who has a good roof--doesn't matter how many screws you have holding your roof sheets down, when the whole lot gets peeled off because the battens were nailed down, not screwed down. Or your garage roller door blows in--no one pays the extra for a cyclone rated roller door, --and bang, your house explodes.

So, to sum it up--don't overthink it. Worry more about your house than your boat.