What you have labelled as "R2" is actually "R1".
Because of the door, the right side 2nd row belt mount is much further back than the left side. In the Wagon, there is a small hook above the door to stow the seatbelt on when not being used.
And yes, you can attach seatbelt directly to the seats. That's now Ford does it.
In case you are wondering...
3-point seatbelts must have anchors good for 3,000 pounds each (per FMVSS).
2-point seatbelts must have anchors good for 5,000 pounds each.
Just mount the seats with a large 1/4 backing plate, and you will be good.
BTW - Not all conversion van seats are actually FMVSS compliant, because they don't have to be. So if you want seat mounted belts, then I recommend sticking with some Ford take outs.
Here is looking back at row 3 in my van. You can see the 2nd row belt in stow position:
And here's the side view:
And towards the front:
This is the only pic of the left side I have (yes, that's 4,000 pounds of concrete in the back):
