I've just donned my 'bivvy nerd' hat and tested the strength of the (very nearly ready) poles. Pressure was applied to each pole until it started to bend. At the point of bending no more pressure can be applied as the pole will just bend more.
What you thinking on adjustable length, extra section or did you get anywhere with the telescoping bit?
I've tried a few ideas but in reality they either end up complicated, too heavy or cause a potential weak point. So it looks like an extra extension piece will be the way forward.
Do you get different results with the pole about 5 degrees off vertical (like I did in my experiment here)?
Just tried with the poles somewhere between 5 and 10 degrees off vertical. The results remained fairly constant, with the only difference being a drop from 6kg to 5kg for the mystery aluminium pole.