put it on when it`s full ,they are a pain to pick up out of the van,but how on earth do you manage to actually put it on,Gaz
I wouldn't carry a full backpack. I think that's just asking for back or neck trouble.
I rarely fill my backpack above half-way, but keep a handy 25 litre barrel close by on a sack truck for quick re-fills.
I also don't wear the thing (or only very rarely) when using the pole; I carry it to where I'm about to work, then put it on the ground.
It's not ideal, but it still kicks the bottom out of using ladders.