I’ve topped on a Mercedes saloon, which has a similar rear. It involved lots of carpet over the boot. I loaded the launch trolley with the wheels on the boot and the front on the rearmost roof bar, held by a block and tackle off the car’s front tow ring. I then slid the boat onto the trolley and winched the lot up onto the roof bars. The bars has strategically placed bolts fitted in the rails to guide the trolley on.

 

It was easy to do with two people but tricky on my own. I finally bought a road trailer, which is sooo much easier.