All the placable structures in each of the zones should be able to be placed outside the zones for decorative purposes. If this breaks the gameplay you could make the ones outside the zones purely aesthetic. I would love to be able to place a table saw in my house, have some apple trees growing outside (or even inside) and even have a chicken coop next to my home. At least make this a possibility in creative.
I just really want to build an overall tool area without having to build a zone for each for them.