What you are proposing will work great for movies. You will likely be compromising some soundstage quality during music listening by burying them in the alcove and not following the golden triangle rule but you may be able to make up for some of that by using DPLIIx. With regard to bass, experiment with your bass control and maybe even stuffing the ports with straws.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated