Exactly what I needed, once I realized slopeless only works with vanilla buildings. Thanks!

I figured it out!

My mod here, in case anyone else is also having issues with the longhouse.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2002781355

So hey, this is entirely unrelated to your specific mod. But as you made this mod, I thought you might be able to help. I noticed I'm having an issue with the default longhouse structure. For whatever reason, it isn't acting like all the other buildings slopeless affects and letting me place it anywhere. In fact, the base of the building seems to default to some position so low it is partially underground. I think that's why it won't place. I can't adjust the elevation, either.

Is there any way you could make for me a little mod that corrects this?