I don't load a heavy bike on the back of my van - just a scooter. The rack only weighs about 40 lbs, and my scooter is only 125. But the rack is rated I think 400 lbs. There are other aluminum ones out there that will go 500+.
When I run my Stowaway 2 on the back loaded with stuff, it's around 300# total. You can't even feel it back there.
I attribute this to the excellent weight distribution of the Travato. People may knock the design expertise of Winnebago, but on their conversion, they end up with a nearly 50/50 weight distribution. Excellent for handling, and gives you some wiggle room when you put some weight on the back end. Also, the distance from the rear axle is alot shorter than what you'd have on an XL Sprinter, so that has to help too.