One point to consider is to not have the bars too close to the roof. Mine were factory fitted on our Laika and there's a really small gap about 1.5cm in-between the roof and the bar, this makes it difficult in some cases to use them and it would have been better to have them sitting slightly prouder. Most kits I've seen are pretty much modular ALU profiles cut to length with end stops.
Don't know if your van has side rails on it like mine but if it has and you know a welder what I did was used a second hand set of roof bars for an estate car cut in half then I had a section of steel box section welded in the centre of them cost me 45 in total ( bars £25 of gumtree -£20 to my mate for welding) easy removed good roof clearance and I expect they're much stronger than bought ones
No we have no rails at all. I would love to know about the quality and strength of the Fiamma ones. We will be carrying two kayaks and sometimes a 15.5ft open canoe. Don't seem to be able to find any feedback on the Fiamma offerings.
Hi Sandra go to a fabrication place that will make one for you --there are also places on ebay that make ali back boxes they may make one up for you --Remember Stewart's back box -nice kit and did not cost a fortune -sure they would make a rack up for you --