2006 Sprinter-based RoadTrek seat belt questions ?

Greetings B people.

I am doing a conversion on a 2006 Sprinter 158 - the same platform as the Roadtrek 22 of that year.

I'm trying to work out comfortable safe seating for rear passengers. Most Sprinters use integrated seatbelts built into the seat but Roadtreks from 2006 had belts attached to the pillar.

If you have one of these and would be willing to share description or photos, i would be grateful.

Thanks