Either they can be made to fit....or they can't!
Good thing you've got that "guaranteed fit" policy on your side.
Haha, seriously though....Can you share some more details?
What model/year van do you have? (And what axle?)
And what make/model/size rims did you purchase?
If your wheel won't clear your rear hub, I am immediately suspicious of the fitment match. Curious if you bought a "universal fit" wheel design of some sort, vs. one intended specifically for your van? The various OEM manufacturers (Ford, Dodge, Chevy) do indeed in some cases share **bolt-pattern specs** across some vehicles/applications....but will still often have significantly different dimensions for their **center-bore openings**. (The big center hole that it sounds like won't clear your hub.) This center-bore spec can be easily overlooked when someone claims a wheels is a universal fit....
If you could, it would probably help if you posted a link to the CarID listing for the wheels you've bought....and perhaps a photo of your rear hub to better identify what axle you might have. With that info, the brighter minds here on the forum (translation: probably not me, lol) can likely better help sleuth this out.
(Brief opinion: Solving it with spacers seems like it would require a custom-fabricated "adapter spacer"....and there's got to be a simpler (and cheaper) solution out there than that....)