Ok, thanks! I just found a larger spot. And as mentioned above, you need to dig up after to have more space. But Imo nothing really useful to build larger bases. I found something on yt and wonder hows this possible. :)

https://steamcommunity.com/sharedfiles/filedetails/?id=2982611818

https://steamcommunity.com/sharedfiles/filedetails/?id=2982612528

Looks quite a bit patchworked.