Remember, it’s not the bed that needs to be longer, it’s the side rails that need to be longer, and I’ve already planned for (and explained above, in the OP) that the rails would be of some type of longer wood or lumber. EDIT: I referenced them being cut from 1" x ?" x 10’. However, as per Ryan, it would be better to use an engineered wood, even if it has to be two pieces glued together. To quote Ryan:
And again, him answering me asking what to do instead of dimensional lumber: