I had a similar problem with 3van windows,what I did was fitted a Aluminium gutter flush with the top of the window frame,the Aluminium gutter has been cut about 100 mm wider than the window frame,I have fitted the Aluminium gutter with double sided tape from Repco the same width as the guttering that's 100mm each side of the window frame ,since I have fitted the gutters we have had some heavy rain guess what no leaks seems they have done the job,I had trouble with the front boot leaking as well, what I did with it was fitted the Aluminium gutter at the bottom of the boot lid but upside down,what I think was the problem there was while driving the wind was forcing the water up under the bottom of the lid,this experiment has not been tried as yet,plus a new boot rubber fitted to the inner edge,see what happens in about 6weeks.
ps I got this idea off another vanner I asked about the heat with the double sided tape, he said not a problem in 40 degree plus heat, a plus not having to drill holes.
Lance C
-- Edited by Olley46 on Saturday 21st of June 2014 09:45:11 PM