How far and/or how long are you looking to drive before you get to your destination and can plug-in? Might I suggest the simple, low-tech approach: plug it in a day or two before you leave to get it nice and cold, and then take a gallon milk jug that you filled with water and froze in your house freezer, and place that in the fridge and close the door. A chunk of ice that big will keep your fridge cold for a considerably long time without the fridge being "on."
2015 XLR Hyperlite 30HFS5 (mods being performed regularly)
2009 Salem LA 292fkds (gone)
Nights- ('12)23 ('13)23 ('14)15 ('15)31 ('16)25
2014 Harley Davidson FLHX (XLR cargo)
2014 VW Jetta TDI (diesel sipper, camping support vehicle)
2011 Ram 2500 CC 4X4 CTD, B&W Companion (toy hauler hauler)