Roger:
I have a similar situation with my 2 channel HT system. For this type of placement, acoustic suspension speakers (like the NHT SB2) or front ported speakers (like the Omega Super 3; Wharefedale Diamond 9.1) will work best. Rear ported speakers, even with plugged ports, will not satisfy you. I learned this the hard way with KEF Q55's and EPOS 11.
In my 2 channel HT system, I have had the best success with Acoustic Research 302; NHT SB2; and Omega Super 3. The following is a description from my 2 channel HT system
... The sound is close to the sound of my main system, but doesn't have decent soundstaging. This is attributed mostly to speaker set-up ... horizontal placement on shelves inside of bookcases, sitting about 5 feet high. The speaker set-up looks like this: [o O] [O o]; with the tweeters on the outside. It works well enough as the speakers are an acoustic suspension design and can handle near wall/shelf placement. The sound has decent clarity and punch to it and is probably where most of my music listening is done.
At some point, I think that you will wind up selling the Rainmakers and pick up something designed to work well on bookshelves and/or close to rear wall placements.
Reagards, Rich