Being a 'thickie-Geordie' I just cut the spray attachment off and stuck a female hose-lock connector to mine.
It works for me!
Get yourself one of those collapsable sack trucks, and hacksaw a larger opening at the bottom so you can get at the button in the base of the back pack.
Also drill a couple of holes in the sack-truck's base and put a couple of bolts in there to raise the base of the sack truck from the ground; so you can get your fingers under it without having to tip the sack truck back.
It is a good bit of kit, but it takes a little bit of getting used to.