inverter recommendation

I own a Benimar mileo 202 motorhome with a 100w solar panel and 2 x110ah batteries. My question is what would be a suitable inverter to have fitted in order to re charge electric bike batteries that take 2amps charging for max 4 hours. Some one suggested just plugging in an inverter to the 12v socket and connecting the battery charger to that, is it really that simple? Apart from LED lights and a drop down bed there is no other draw on electric. Any advice would be appreciated..