Not entirely sure which type of rhino rack you're referring to mate but if it's the ally tray that bolts to a set of rhino cross bars (either commercial or aero) then yep it will fit. I have one (2 metres) with 3 commercial bars on my GQ, and I lent it to a mate with a GU for a month for a big trip he went on.
The GQ gutters are parallel and a bit wider, the GU is narrower all up and also narrower at the rear than it is at the front, so we had to adjust the feet. Also we had to change the little brackets that clamp UNDER the gutter, not the actual feet themselves. The underside of the gutter on the GQ is close to parallel to the ground, but the GU is angled down toward the middle of the car. These brackets were only a few dollars from a rhino retailer.
Even if you have a different one, as I-1 said as long as the feet are width adjustable I'm sure you could fit it in exactly the same way.
I priced a set of 4 feet that go under the rain gutter to adapt the GQ bars to suit GU through autobahn as I have a cab not wagon and the feet and postage we're going to be $100 so I didn't I will just get 2 new rhino Bars complete about $320 /$370 depending where you shop