Just remember that if you put ANYTHING on your rear bar it will void the warranty - apparently. I asked about our rear bar as we have the same and asked about a bike rack that our in laws have that would clamp on. Got a very emphatic "No".
It is stated in your manual about it as well.
However, in saying that, I think under Australian law, they would have to prove that your mod caused the issue in the first place. So say your stove stopped working, they would still have to honor it, yet if you had a crack somewhere or a cupboard no longer shut etc, they may come back and say that your mod caused undue flex in the van.
I know a lot of people on here have added to the bar, but I believe a lot have also extended the bars under the van to give extra strength.
Just my opinion but I also play safe in a lot of things.
BJ