i would definately go for a trolley over a backpack
for a £1000 kit from pure freedom, will include a trolley, ro, tds meter and pole all delivered to your door then all you will need to have is a outside tap a water butt for the pure water to go in and then some 25ltr containers to transfere it
its up to you how you work but if you are working out of a car i would do all upstairs wfp and downstairs trad just use your ladders for access
best of luck
Brett