Personally, I don't see a problem with a 30 footer. We're not fulltimers, but the DW and I have traveled for two to three months at a time in our 33 footer with one slide, including staying in one place for two months. I remodeled the interior to suit our needs including removing one sofa and replaced it with a desk and recliner and added a fold down table mounted to the wall between the slide and wall for extra countertop space, which was small. We never got in each others way.
What I'm saying is you can make anything work for you if your happy with the layout.