The lights you want are 12v bulkhead lights. You will get them from either car /commercial vehicle electrical merchants. Another supplier would be trailer/caravan or even boats chandlers. the flourescent ones are OK too.
The wiring may already be there, if not make sure you use in-line fuses(best one per unit) because it is easy to damage them when loading or unloading the van.
They are also available with the fuse inside the unit and also magnetic for the roof where you can't drill.
