In those circumstances I would hire a skip. Bearing in mind the cost of your petrol, and the size of the skip it would be easier, imo. You can spend more time emptying the house, and less time driving to, and queueing at, the tip and putting things in the right receptacle. The sisters can then pay one third each of the cost. You do not risk lots of creepy crawlies in your car.
Last time that I had a skip outside the house, I put things at the side of it, and then some people had a use for the item, for instance
Giant sheets of bubble wrap went to someone for insulating their green house.
Large quantities of clean cardboard went to a second hand book shop
Old hot water tank went to someone who was building a ground source heat pump ...water "wotsit".

Lots of plant pots (small, black, non-recylable) went to someone starting a nursery.
Garage door was given to someone whose garage door was even older than mine.
I think the skip was filled three times over, but only collected once.