Suzuki Club UK

I want to fit a proper expedition style roof rack to my 98-05 lwbGV which I've recently bought. Has anyone done this? My plan is to unbolt the fitted roof bars and use the bolt holes as my mountings for the rack which I will make from light box section ( I have done this before with other makes) It is the mounting that is my concern. I would really like a support midway along the side and don't want to drill the roof ( other than down in the slot perhaps), is there any way of fitting to what already exists? (in past vehicles they all had roof gutters for which I bought brackets and welded on to the rack) Are there any websites etc that I haven't found yet?
thanks, Phil