I started with a DIY trolley years ago and have stuck with it, My son now helps me 3 days a week and he has one too. I use a trailer with a ramp and it's as quick as any van mount. I don't have to fill mine, just change containers. I'm pushing 70 now but can still manage to push the trolley with 2 x25ltr containers up the ramp.
We have enough containers so that my Mrs can fill the ones today that I will use tomorrow. I get home, chuck out the empties and fill up with full contaners for the next day.
Having 30 meters on a hose reel mounted to the trolley means I don't have to take the trolley round the backs, we don't have the parking issues which with constantly moving the van Either.
Most of my work is really compact and this system works for me. I could fit a tank on the trailer if I wanted, but I'm happy as I am. Each to his own, it's horses for courses. 14 containers brings in about £250 between us, but I like to finish early these days.