Backpacks/trolleys do have their limited uses and have their unique set of pro’/con’s too. I suppose it depends on the work you want to take on as if it’s still worth the hassle to do in the first place really.
After using a pf trolley when I first started and found it to be a real ball ache to use I never really wanted to go back to using one for domestic wfp work after getting tanks fitted to the vans.
I believe smudger made a couple of large trolley systems for large inner courtyard jobs that he won to overcome the issue of trailing houses through the buildings but I’m sure it paid him handsomely for the hassle
After saying that I would not mess about with a backpack/trolley taking it through someones house now. It seems quite common to see backpack newbies clambering over garages, pitched/ flat roofs, locked gates, fences etc with a full backpack strapped to their back...Bless em