Here is the rear seat delete we are working on currently. So far with the vinyl and both boards, it weighs 13 pounds. The board we are using is the stuff that you put on floors in houses before installing floor tile or whatever.
With all the brackets and seat belts. I think it all weighed in between 45-55lbs. I cant remember the exact weight with the rear seat belts removed. I think they both weighed around 5 pounds each.