I know exactly the kind of trolley you are looking at, i have been thinking about getting one myself, though not for work. I live pretty close to a supermarket, and to save taking the car out for such a short journey, i had thought about using one for the weekly shop!.
But back to your question, as long as your round is compact, there is no reason you couldn't use one, and it would certainly keep you fit!. You could probably manage a 200l tank (so long as you don't have to contend with any steep hills), leisure battery, pump, couple of poles and away you go!. You would have to pay some attention to security though (both to the trolley itself, and your kit), and also some kind of brake to stop it rolling away.