I had a Fiorino 1.7D between 1999 and 2002 although I wasn't window cleaning then.
I found it to be very reliable although it was a bit gutless for the longer distance run; I occasionally journied from Staffordshire to Newport, [the one in Wales] and did a couple of journies to Dorset and to Devon.
It doesn't have a turbocharger if I remember correctly, but, look on the bright side, the turbo won't go wrong, will it?
Suitable for towing a brace of ladders around locally. I'd have thought.
The main advantage I found with it was the space in the back; I used to carry two old mopeds to shows and I could stand them both upright.
I've had two Kangoo's since then, and they are cramped by comparison.
Change engine oil well before the makers recommendation and periodically have the injectors cleaned/replaced every 100 000 miles or so and it should see you through!
Baldeagle