no seats, no overhead bins, no lights, no IFE, no lavs, no F/A jumpseats, no galleys (did I forget anything?), only two doors with no slides, so basically nothing but the floor for the main cabin

Actually I would like the weight of such a plane plus 42 business class seats upstairs, but if I can get the empty weight then I can estimate what the total would be (it depends on the amenities the top floor pax get like IFE or overhead bins or emergency slides lol).