I wouldn't put another cage on top of the Barney - it's long and the bars aren't that strong so the top would bow under the weight. Plus as mentioned above you really need to use the top and side doors for reasonable access.
I was also going to suggest something from Ikea which is cheap and the right size. It's true delivery is expensive (and tends to be slow) but might be worth it if the item is cheap enough!
I've looked at things on Amazon but never found anything cheap. The Alaska would fit underneath and the Barney on top
https://www.ikea.com/gb/en/products/...-art-30128629/
You can get the Linmon table on Amazon. It's quite tall but you could always shorten the legs.
https://www.amazon.co.uk/IKEA-LINNMO...ds=ikea+linmon