You can put the Blades 9 inches from the front wall (per KEF UK and the manual). The Reference line needs 1 foot.
If you put the Blades along the 19 foot wall it would work rather well. Other people have put the Blades along a 14 foot wall but I think that would be a waste of the Blades ability to create a massive soundstage.
I will put mine on the LONG wall which opens up to the Family room. I also have 25 foot ceiling, so when you add up the volume of the space it is like a big room. Volume is important to consider because the Blades have bass.
The online Stereophile review of the Blade 2 talks about room size and the Blades. That review was a bit puzzling. More info about the music reviewed rather than writing about the speaker.
I spoke with Vivid Audio about their side firing woofers and proximity to side walls. They said it depends on the building matter used in the walls. I think brick was bad (I need to search my emails).
If the room turns out to be too small, and you are a ROON or JRiver streaming user, you can contact Mitch Barnett at Accurate Sound and let him do his magic on your room + speaker + placement = accurate sound.
I used his remote service for my small office when I had Thiel CS3.7's in there. I doubt I will need help setting up the Blade 2 in my Livingroom, but that security blanket exists for me. He does an incredible job.
Search on A'gon if interested. I wrote a lot of my experience using the Convolution filter of ROON that was created by Mitch for my room and speakers.