I would suggest you go out and buy a D/C car stereo CD player and speakers. It will take up much less space and will not drain your
battery nearly as fast as an inverter will. Adding a
solar panel will help keep your
battery bank charged up. Your inverter could be used for computer and small power tools etc. for short lengths of time, provided you have good batteries and a means to charge them. You never want to drain your batteries to less than 50% charge as they will never hold a good charge after that. I recommend using 6 volt golf cart batteries in a series to make 12 volts. They can be drained and recharged many many times without ruining them.