put the 650 back in fill it 3/4 full if it lasts hey presto your not dragging 150kilos everyday for nothing.
Also if you have a guttervac get that out the van. my ladders only go in the van 2 days a month, yes in the van double a frame in a scudo, i only use for flat roof access and a bit of commercial internal. all this excess weight makes a hell of a difference to your fuel bill!
I work on my own & have a 300l tank btw and empty it daily. in the summer i may refill or if i have done a big commercial job in the morning, but most days when the tank is empty im done. Im upgrading to a 500l in the new year, wont nessascarily fill it to capacity everyday though.