My 2003 Kountry Star came without an inverter. Any recommendations? When boondocking, would be nice to watch TV and run the computer. No 12 Volt outlets in the RV, just 12 volt lights and one outlet for the radio.
There are 3 types of inverter. Square wave is cheapest, but puts out really crappy power. I wouldn't plug anything costing more than a dollar into one Modified sine wave is the most common and is fairly reasonably priced. It will cause some things distress. Microwaves don't like them, and oddly enough, they seem to encourage 'wall wart' failure. The best (and most expensive) are 'true sine wave' inverters. Your electrical equipment can't tell the difference between this power and the stuff you get out of the socket.
As for size, depends on what you will be powering, and where you get the power from. Small ones plug into 12 volt sockets and power small gadgets. The ones which handle a whole trailer have to be close to the battery bank, and have a huge cable powering it.
You can look on the units you will be powering and see what the wattage is. It will either give you watts, or amps. If it gives you amps, multiply by the voltage (120) to get watts. Add em up and this will tell you what wattage of inverter you need. It would probably be best to round up and/or add a safety factor in case you add something or replace something.
Once you know which inverter to get, you can find out the amperage requirements of the inverter. Find a 12 volt source (wire) which will handle that current (large enough guage wire), hook up to it (making sure the wire to the inverter is appropriately fuzed) and you should be good to go. Your best place to hook in is right at the fuze box, so you are not adding a large draw to an already existing wire which may then be overloaded. Do NOT use an ignition switched source, as you don't want to have to turn the vehicle on to watch TV, and it is frowned on to have a TV visible to the driver while the vehicle is running.