I haven't worked that high, the highest so far is 40 odd feet, and that was 4 storeys
If you are going to 'T' into your feed, just use GG3 or Unger liquid, in very dilute form!
When yo uget down to lower heights just dip the brush into a bucket with a normal solution of GG3/Unger liquid or other specialist window cleaning detergents.
As you have been using WFP for 3 years you know you have to go over this work a few times, rinsing thoroughly each time.
Adding a little detergent (not washing up liquid of course) can certainly help on a pig pen clean.
Over on another forum there are quite a few threads on the subject.
Ian