I totally understand regarding brand new van, not wanting to put holes in roof, thing with me is I have van 12 months from brand new but I will run this van til it dies I won't be looking to sell on so am happy to do this.
4 x bolts
4 x metal washers
4 x rubber washers
It don't leak, so it's all day.
I have emptied my van to paint floor so will post pic of how I done it tomorrow before new system goes in.