That is a American Queen-sized bed but the frame I got from Europe via eBay. So I took the sides and made a tongue with a jigsaw. That way I can extend the length of the frame. The frame does not support the bed, you can see the little legs under the box spring, another "Euro" type setup.
The headboard was where I wanted the strongest structure. Thankfully, the headboard was where I could use through-bolts. Here you can see eight 1/4-20 bolts securing the L-bracket. I intended to have fender washers under all the bolt heads, but I am unable to count past the number of fingers I have. You can see the washers pulling in from crushing.