I installed the side rails for my Rhino Rack Pioneer Tray this week. I was also able to mount my spare, hi-lift jack and gas bottle up there. I'm still waiting on my Rhino Rack Small Luggage Bag to go on the front of the tray.
When I realised the tray weighs 20kgs and my spare tire weighs 38kgs, I started to get a bit worried about the 68kgs weight limit. Realising I would be over the limit, I researched tow hitch spare tire carriers as well as all the information I could find about the roof weight limit. After lots of internet searching and some helpful advice from Rocky Road Outfitters in the US, this is what I found. If your roof rack/tray is mounted to the bolts in the roof and NOT to the stock rails you should be fine to slightly exceed the 68kgs limit without damaging the roof or having anything fly off. The roof is made to withstand 4xGVM for rollover protection and is definitely capable of holding more than 68kgs. RRO regularly puts well over 68kgs on the roof with their racks. Having said that, you should be very careful putting any significant weight on the roof of your car. It drastically changes the weight distribution of your car, (i.e. making you top heavy).
This weekend will be the first off-road test with everything up top. I'll report back on how things go.
Here are a few photos: