Originally posted by Jitatha:

Warchild has answered question, however for the non-modders, you can make a box room under (or over) the room you want, then the bonus will radiate up to where you want. So can put the rugs, chairs, table and bed out of site behind or under a wall. The same works for workbench add ons.

Oh, I probably should've mentioned that, I do the same with my workbench/forge add-ons, but the OP did ask for a mod.

My first ever hut was built on uneven ground, so it extended out with some dead-space below it that ended up being perfectly suited to addons for the workbench above. Then when I actually designed a workshop, I had a hidden loft in the roof cavity that had all the addons in it. It worked so well that I'm guessing this is what the devs had in mind.