Again I agree with John re. Kitchen Sink Marketing.
If you've completed all the chat with madam, why not carry at least 2 buckets for fresh water. If the tap fills quickly you can fill one whilst transporting the other to your machine and so on. If it's a slow running tap, rather than stand around doing nothing, you can "Multi Task" by doing such things as connecting hoses and power to the machine, pre-spray or pre vac etc. etc.
If you are serious about using a porti as a sort of mini truckmount, what about this route. A CFR 1000psi (forgot model name). They hold about 15 gallons. This is a working equivalent of upto 105 gallons. Plenty of water pressure for the longer hose runs. I don't know if it would work with a CFR, but would a Recoil Booster be a viable option to increase hose length further?
Safe and happy cleaning:)
Ken