My basement listening room is larger than the o.p.’s, but concerns about placement are, in this case, IMHO, unwarranted. The Vandersteen 2Wq is designed to sit in a corner, so the issues of boundary reinforcement are already baked into the cake. And, no surprise, my pair of 2Wq’s sound terrific in the front corners of my room. Also unwarranted, IMHO, are concerns about blending these with your mains. The unique hook-up scheme presents the mains and the 2Wq’s with identical output signals. So, if your mains reach down to 40Hz (and yours do), you are good to go.
I don’t know where you are located, but John Rutan of Audio Connections in Verona, NJ, is an expert in all things Vandersteen. Short of calling Richard himself (he’s not that hard to get on the phone), you could ask John Rutan your question.
Also, having upgraded from the in-line filter to the battery biased crossovers (MHP5 ?), I can tell you that it well worth the added expense and battery changes (they are soldered in, and should be changed every 10 years). You will get added transparency.
Lastly, it is generally recommended to mass load the cabinets. In my basement, where looks takes a back seat to sonics, I use boxes of tiles and ammo on top of each 2Wq to mass load them.
But, hey, YMMV.