As far as the seats for the CrewVan, you can install the 2 passenger 31" or 36" or 3 passenger 54" seat in the existing floor mounting brackets. You would have to add a floor mounting bracket to go with any single 16" seat.Do you have any 1 or 2 passenger units in that color? Does any single fit in the 2nd row center position?
Right now I have the 2 passenger 36" or 31" Ebony Cloth in the XL style seat (NO recline or armrest) and a 16" single seat in the XLT trim. Dark Palazzo Cloth I have the 36" 2 passenger XLT seat and the 16" single seat in XLT trim. If you decide to add a floor mounting bracket for installing a single seat, I have a bracket to go with the seat so you could install it.