additional seatbelts

Has anyone added additional seatbelts to their unit? I have been looking at a Hymer Sunlight or used similar Travato and would like to have seatbelts added. I am thinking that it would let me use the unit more often. I know I would need to have a welder reinforce the floor areas for seat belt connections and be creative with strap placement. There is no reason to put the seatbelts in if they are not going to serve their intended purpose. I know the larger coaches have seatbelts on couches and dinettes. So has anyone done something similar in their class B.We do not like the rear couch that makes into one big bed where they come with belts or this would be simple.
I am thinking this type of vehicle would make an acceptable 2 -3 couple transporter for 1-2 hour trips around home. I realize that the seats may not be that comfortable for a long ride but for a short ride it could make for a nice transportation vehicle.