My Takena 1865ex had the same problem until I asked them to fix it during a trip to the manufacturer for something else. When the trailer came back, the lav door cleared the slide and everything was fine. I think it was just a matter of making that carpeted step on the slide a little bit smaller.
I love my Takena, Nice small size on the road and in the driveway, big room on the inside when camping. And my 6'4" husband stands up inside with no issues. Also love the large capacity waste tanks. I hope you can fix your door issue so you don't have that one pesky annoyance to think about.
Enjoy!