Artisan Bespoke weight of mattress

Please could you tell me the weight in Kg of your Artisan Bespoke in Kingsize? I am interested in making my own storage divan style bed with a slatted/pegboard top which hinges up with the assistance of gas struts, available online. I would imagine that the commercially made storage beds are designed to cope with much lighter mattresses. Do you have any experience of this?