In my business we get a lot of sample products.  One of them
follows this particular vein.  It's called "Hot Jet" screen
wash.  First off I can't recommend it because I have not
bothered to take it out of its box.  Second I have never seen it
in a store.
What it is... a plastic box with the inside hollowed out to fit
around a radiator hose, two zip ties, and 10 feet of plastic 
hose.  The assembly is very simple looking, as you might
imagine.  The box sets on top of the top radiator hose, the
tubes are routed through the box and back to the washer.
  The product appears to be from Canada.  The only address I
have is Cross Border Marketing, Van. B.C.  Made in Hong Kong.
  This might be easier than creating your own setup, I don't
know.  Good luck!!!!

Matt Rathke
City of Seattle
**Opinions are my very own, of course**
'73 Bus.