[jouk45]

i still say this is the answer for the trolley set up, its easy to install, has a build on switch, all though it only gives about ten good bursts of hot water, every 30 seconds, i think that would be enough to help get rid of a lot of stubborn dirt,   the cheapest i could find was about £91, better than £160, i mean you dont need loads of hot water, it would be a good accessory   to have on the trolley

  webasco hotshots

      THIS CAR WASHER HEATER WOULD BE VERY EASY TO FIT TO ANY TROLLEY SYSTEM. YOU EVEN GET THE SWITCH WITH IT
 HERES THE LINK   http://www.crutchfield.com/S-YWk9K5nd8Bf/cgi-bin/ProdView.asp?g=274450&I=646HOTSHOThttp://www.crutchfield.com/S-YWk9K5nd8Bf/cgi-bin/ProdView.asp?g=274450&I=646HOTSHOT

[jouk45]

 This is how easy they are to fit, its so basic you can fit it on your trolley in about 30 minutes,
dont look at it as seen in the car bonnet, just imagne it connected to the trolley or backpack, also there is hardly any weight at all in the device