Dan, get the most reliable van you can for the money. It needs to work every day and that's the most important thing when you're on a budget. Don't worry about what make it is.
I had a SWB transit connect for 11 years. Been cleaning for about 6 years and I got a 350 tank, 2x 25l barrels and everything else in. 22' pole, plus extensions, plus ladders, plus trad gear, chems, brushes, spare hose for FSG cleans, cones the lot.
It was brilliant but I needed something bigger.
I have now bought a mint Toyota Hiace (high mileage) but one owner and full service history for 3.5K. I also know how it's been used and what it's done. I've spent 9 months looking for one but this baby has been looked after.