I have had a TM for over 5 years and NEVER had a freshwater tank.
I use a hoselock retractable hole and reel, and carry a spare hose and reel. I have lots of different connectors for square, round, weird and strange taps, plus those to fit on to the outside taps. A trip to B&Q and buy all the different types they have and you can not go wrong. Most custards (90%) have outside taps.
And I am not the only one with this set up, as I stole the idea from Phil in Northampton, who tok it off David in Scotland and so on.
Why bother with carring all that weight in water, extra fuel use, when their is an alternative.
And before anyone starts, I am not saying this is the best way. Having the water on board must make life easier, all I am saying is its an alternative, and one that works very well.