Please take this as some gentle well meant advice from someone who has used these poles since January last year. You can just raise from horizontal at 42ft with a brush thats less than 8oz but.......
But I do not advise it for two reasons. The leverage on the pole joints is awesome, the pressure is applied at the very tip of each joint and can cause the possibility of a stress fracture paticulary if there is a already a slight hairline crack.
The second and more important reason is your body. You can and will do more things with the poles, going to difficult situations just because you can reach over under, up and across, its so easy. But the downside is you body takes strains it shouldnt have to and you may well suffer small injuries paticulary reaching at low levels using your leading arm elbow joints and muscles. They can quiet easily be put into strain injuries, muscle spasm etc. I have been there.
There is no need, it is generally faster to raise say 20-30ft from horizontal and then just add remove the last few sections when upright in a more balanced and controlled way. The whole oif the pole and brush can be held upright with just one hand.
This applies with trad wfp poles as well, dont go over your or the poles capabilities.
Hope this info helps you.