I know I and many others are frustrated with the limits put on sandbox, a mode where you are supposed to be able to do whatever you want. I suggest a separate mode or toggle that lets you ignore placement rules, use any materials on any item/surface, and build walls outside the limits of the property. It's not a coincidence that most top rated houses on mod.io make liberal use of resizable shapes and custom textures. This game allows you to build some really cool stuff but it feels like I'm always fighting it to get it to do what I need.