ok to put my bipole/dipole rear speakers in bookshelf?

[STARSCREAM]

Question for you guys, my Polk fxi a4's I'm using as my back rear surrounds have to be placed in the huge bookshelving that flanks both sides of the fireplace. Now, I still don't have these wired up but is this gonna be ok? I'm just kind of concerned since they are bipoles or dipoles (depending on the setting) with the sound bouncing around in there off the left and right sides of the shelving.Or would this actually make it better?

I just measured and there is 1 ft. of space on either side of each speaker before the shelving sides.