got same van,cheapest probably gardeners,peter fogwell at aquatec sells frames for £120 i think.got to drop fuel tank if you fit around chassis though.i got some angle iron for about a tenner and a couple of high tensile bolts around the chassis but there is a big void behind seats so just some bolts and spreader plates for that side of tank,2 ratchet straps to hold in place.if i get bigger van will get frame from peter.