Sorry to be different, but i feel a detergent rinse makes a big difference in the results i get. There are jobs where a prespray and pure water rinse will suffice, however on the whole i feel extraction solutions give that extra edge.
The way I get round that at present is to have a 12v pump (like your window cleaning pump) fill the machines tank. I then dose the chemical in there as needed. I can leave it to auto fill as there is a valve fitted in the tank, and the pump shuts itself off when it detects a dead end. I just fill and re dose the tank using the pump next time i vac and prespray.
Of course like mike you may find a pure water rinse adequate, and wont need to bother with any of that.