I got rid of the van about 6 months ago and built a trailer. the job has become so much easier. My trolley can carry 2x 25 liter containers, and I can wheel it up the ramp so no more lifting, I do have to change containers of course, but don't have a problem with that.
10 containers will get me through a heavy days work on compact houses.
The 30 meter hose reel that's mounted on the trolley is what makes it so much easier, I never have to take the trolley round the back.
I really couldn't be doing with moving the van every 15 minutes, only to have to move it again when in the middle of a job because someone want to get in or out of their drive.
Using the car means only using one vehicle, one tax and insurance, one MOT.
The only down side is that I no longer have my belt and braces, if the car is off the road for any reason I couldn't work, when I had the van, I had the car as a back up.
A van mount would not be suitable for most of my work.