That configuration doesn't exist in the 2020 ordering guide, however you can order the Passenger Van with all the rear seats removed but the attachment points present. The rebated value wasn't much for removing four leather seats ($340) making it an 8 seat van, but I didn't need the extras.
Those single seats show up in the Classifieds here regularly with people gutting rental vans, and your easiest option would likely be to get the Passenger Van with all the seats removed and piece together the ones you want. You might get lucky and find them all from a single new van, but given how long it takes to get a a van ordered and delivered, you'd have more than enough time to find them one at a time.
But do notice those rear single seats have different designations ("F", "Q", "Y") in the ordering guide, so you might need to be very specific with a seller if they are for the 3rd, 4th, or 5th row.
If you only need room for 2 more in the rear, did you consider the "D" seat pictured for the 14 seat configuration in the second row? My plan for my 8 passenger van is to remove the "K" seat and move the "D" forward.
The 8 seat configuration gives you the minimum number of seats in the LWB model and you can switch the 3 passenger out and move up the 2 passenger seat in its place. When I worked with Ford in 2018 to offer the 'delete' seat packages, they were not willing to go with different specified seating in the passenger van. What you see in the diagrams above was what they decided to offer for the 2019 and one of the best features I asked for was changing the single passenger seat from a bolt-in seat to a quick release seat that makes the floor flat when ALL of the rear seats are removed.
One configuration that was really wanted and Ford took away was the 11 passenger seating, So many buyers like the 2 passenger second row seat instead of the longer 3 passenger seat. It gives you more room in the second row area and if you are placing a child in the child seat, you can stand inside the van and place them in the seat whereas you may be standing part of the way outside the van with the 3 passenger seat.