Bill and I purchased wireless speakers which connect to power (we ran a cord from the outlet on the bathroom wall near the inverter box to the bed pan and up to the center back of the bed and enclosed it in "on the wall" conduit) and the amplifier connects to a power source near the TV. The amp connects via audio output from our flatscreen DVD/TV. For those who are not audophiles, the sound is acceptable and adjustable in volume at both the speakers and the amp.
As for mounting, we used velcro mounted shelving from
www.shelfexpressions.com. The corner units mount nicely on the back & street and back & curb side walls. We used the 24" high shelves. The shelves also allow us a "night table" as we only use one speaker per shelving unit. Be sure you use clear industrial/marine strength velcro and clean the walls with alcohol before application. MORE IS BETTER when it comes to velcro and shelving. A word to the wise--place the velcro exactly the same on each shelf back. It makes installing the units easier as you don't have to worry about which one goes where.