We have run a VCR and a 13" TV on an old 150 watt inverter, but these were old and both had power transformers.  A friend tried to borrow mine and a second one and neither would operate her combination TV\VCR.  It was explained to me that all the newer electronics use a "switching power supply" and prefer power like you have at home, 110 volt 60 cycle sine wave.  If you find someone with a large selection of converters, you will see a price range for units of the same wattage, the difference being "square wave", "modified sine wave" and "pure sine wave", etc. I'd hook up to the vehicle battery and run an extension cord.  That way, each day you drive, you recharge the battery you have been using.