i like what youve done there Chriss. Good strong fittings, i would do this rather than buy an expensive thing, these metal fittings i have never had leak, and you have the benefit of not having to fiddle with varistreams all the time, just leave it on all day, & two outlets from the brass fitting. This must work off one pump.
Or if you dont want to drill holes in your shiny vans, then if you look underneath where the spare wheel is i think, i dont know but on cars where the spare wheel is under the boot, there are plastic plugs in the aluminium you can pop out to let any water out that might have got in there, just pop em out and put the hose through there and fix something underneath.