No opinion on pressure / non-pressure. Whatever serves you best, I'd say.
But on the jerry cans versus a "tank"... last van (Sprinter), we started with jerry cans: two fresh, one gray. Basically found that a square water tank provided quite a bit more water without wasting as much space - just how things fit in the square space under / inside the galley. They stacked on top of each other and fit front-to-back in the galley we'd built - effectively losing 8" of width front to back. We still had about the same quantity of fresh water; but the shape opened up more space for other usage.
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We followed the same premise / model on the Transit galley; but moved both tanks to the bottom - losing the whole end of the galley, but only 15" tall or something like that. I don't seem to have a photo of that side of the galley (and I'm not at home where the van is); but you can see the fresh tank under the oven in this photo.
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Gray tank is right behind it with the drain facing out the door.
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Down-side to this model, of course, is not carrying a jerry can to a water source and carrying it back full. Up-side is we never had a problem finding somewhere we could get water into the tank.
FWIW, our motivation on keeping fresh and gray inside the rig is freezing temps: we spend time in winter in the snow. So we have 16 gallons inside, 13 gallon gray, plus another 20 gallons /under/ the van - but can't count on that in freezing temps.