I used a xantrex pro watt sw 15amp auto transfer switch.
http://www.bestconverter.com/Xantrex-Prowatt-SW-Inline-15-Amp-Transfer-Switch_p_457.html#.Ut6vtEYo7e4I mounted the inverter near the TT electrical panel and used a short heavy gauge appliance extension cord between the inverter and the auto transfer switch. Fed the transfer switch supply and load wires into TT electric panel. I found the circuit in the TT electric panel that the fridge outlet was on and disconnected it from the electric panel breaker and neutral buss. Connected those conductors to the transfer switch load conductors. Connected transfer switch supply conductors to breaker and neutral buss in panel. Now every outlet on that circuit can have 15a power off inverter or shore power. I got a 1750w (2500w surge) inverter so the wife could use her kuerig, but I have read that an 800w inverter will work great for a small fridge. A pure sine wave inverter is best, but ours runs fine so far off of the MSW. Also, use very heavy gauge and very short length cable for battery to inverter connections. Some inverters come with a remote switch if it needs to be mounted in an inconvenient location.