The upper ball joint in your suspension's I-beams is located with a replaceable alignment sleeve. These do not wear out (made of steel and no moving parts) and your factory sleeves are not worn out, something else has changed (bent, increased weight, worn other component) or they are being way too picky.
These are a $15 to $25 part and there is one on each side of the van. They take about 10 minutes or less to remove and replace. They adjust caster and camber both at the same time. Unless you can visually see excessive camber (tire is more than a degree or two from vertical) I would not be too concerned, and then my concern would be why. Most likely camber would be off in a negative direction because of additional load causing a lower ride height. You might consider new springs instead of alignment to correct negative camber.
Caster you will not be able to see, but if it is off significantly you may feel it in the steering if it pulls one way or if it is sluggish or doesn't want to return to center after turning.
In reality caster is not going to have changed much and shouldn't be an issue.
So that leaves toe as the final setting - this is really the only setting that in most cases you need to be concerned with and it is not adjusted with anything other than a wrench and a measuring device.
Alignment is one of the biggest scams out there.