I can't recall the dealer, but there was a video on YouTube showing off a 2018 3401. With the slides in, the "choke point" seemed to be bathroom/wardrobe area. The guy in the video wasn't exactly skinny, but he had no problem getting into the bedroom area, bathroom, etc.
Now, you might not be carrying your significant other back there, but you could certainly drag them.
And FWIW, I placed an order for a 2019 3401. I also spoke to a couple at Hershey who had a 2016 (IIRC) and they love it.