Lanx0003,
I also have a pair of Buchardt Audio S400 MkIIs, and just a couple of recommendations based on experience.....though I have never measured the room. I am building a new audio room, and have a DSPeaker Anti-Mode to install at that time.
(1) In my experience, 3 feet into the room for the Buchardts is too much, I found the cleanest and most accurate bass at about 20 inches from the front wall; Buchardt recommends closer placement to the front wall.
(2) I'd reach out to Mads Buchardt for his opinion, I have found him (along with Don Sachs and Alvin Chee at Vinshine) to be most generous with his time and help. He frequently posts and answers questions on the Buchardt Audio Worldwide Owners Group.....or just email them, you will definitely get a response.