are you a one man band cleaning mostly domestics and no plans to employ?
if so a 650L TANK IS WAY TOO LARGE!a 400L would do you fine with a trolley or backpack to complement it.
if your a 2 man outfit or mainly commercial window cleaner then a 650L would fit in some connects but i think quite a few on here use transporters and vivaros as its a bit of a squeeze in a connect and you would probably be over the limit weight wise with a full tank.
ive got a kangoo(payload 625kg)and use between 250-350L A DAY using a 50L pure freedom trolley.its fine for now as ive no plans to employ and im mainly domestic with a few commercial.
a 400L would be fine in a connect/doblo/partner/dispatch/berlingo etc depending on which model you get.
im 80% WFP 20% TRAD and find i dont use more than 350L on a busy day in summer.
regards
dazmond