I think you could actually just use the bed as is; but just add 2 twin XL mattresses on top as opposed to a King size. You might need to get some sort of binder like this just to prevent the mattresses from sliding around. https://www.amazon.com/Bridge-Twin-Split-Filler-Adjustable/dp/B07GQ4RSY5/ref=asc_df_B07GQ4RSY5?mcid=c73aa937f9f931f9a43296c96324c545&tag=hyprod-20&linkCode=df0&hvadid=693129581516&hvpos=&hvnetw=g&hvrand=8075569623211007381&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9012572&hvtargid=pla-814543194958&psc=1 . If you prefer separate bases, a lot of people get adjustable beds in a split king size - which is exactly what you want to do - put 2 twin XL beds together. This also allows both people to get a mattress for their specific needs. To do that, you would have to leave off all the center rods when assembling the MALM bed. The bed (headboard, footboard and side rails) should be sufficiently stable to stand up on its own without the center rods; BUT to limit movement of the bed I would attach the headboard to the wall with a cleat. I think that would add the stability needed to actually be able to lean against the headboard, move around on the bed, etc. You would need to lash those bed frames together to keep them from shifting apart and putting pressure on the MALM side rails. You still might need to bind the mattresses. The main thing to check first before going any further would be to get the measurements of the inside of the bed. The outside measurements of the MALM are 83 1/8” by 82 1/4”; but as you can see in the instructions, the side rails of the bed are somewhat inset and there is a small lip on both side rails where the mattress slats sit. So, the inside measurements (especially in the width) are going to be several inches less than the outside. More on reddit.com

I own the NORDLI bed, and I can confidently say its the best choice for your needs. Its foundation is a complete blockage from all sides, ensuring that even a hamster can’t squeeze underneath. Additionally, it’s incredibly stable, with no squeaks after four years of use. However, there are a few drawbacks to consider. The height of the bed may be low for American preferences, but if you’re drawn to the Asian minimalist aesthetic, it would be a perfect fit. Personally, I prefer a low bed that allows me to sit down easily rather than having to climb up. Assembly and moving the bed can be challenging. I wouldn’t recommend it if you frequently move. Each time I moved it, I ended up damaging the bed slightly. There’s no raised edges to keep your mattress in place. The bed is essentially a platform, and your mattress just sits on top of it. However, since you’re using a king-size mattress, it should be heavy enough to stay still. More on reddit.com

How is it to assemble? Easy? More on reddit.com

I think I have the Malm from Ikea and it's solid as hell still, my brother has one that is like a decade old and still holding together well. You gotta get a frame that doesn't have legs. You need large contact areas with the ground to ensure weight distribution More on reddit.com