Congrats for your uncle, if you don't mind who is he?
I have a Koolatron P85 cooler that I got from Walgreens.com for $115 I believe. It's not a fridge but gets down to about 45 degrees in about half an hour and holds 52 quarts. It should keep anything cool and it also doubles as a warmer, just reverse the plug going into it.
it may get the air inside down to 45 deg in that short a time if it's not too hot outside and empty, but I doubt very much it will get some amount of food down to 45 deg in anything less than several hours, if that. The Peltier chips are just not very powerful. Or have you found that not to be true? Easy to check with a few water bottles for example.
Anyway, the point is that if the cooler can maintain 45F, say, (they are usually limited to some fixed number of degrees below ambiance whatever it is, something like 40 F or so IIRC) when empty, then it can also maintain food already at 45F prior to insertion in the cooler at a constant 45F when in the freezer. So, you need to precool the food or buy it cold on the road, before putting it in thermoelectric cooler, otherwise things will stay warm for a long time in there, with possible health consequences. And consider that if it's 100F in the car (say when parked in the sun), it'll be as much as 60F in the cooler, not so great for perishables.
Bottom line for me is I bought one from a major manufacturer a while back, tried it, tested it, and promptly returned it. I thought it just was not very useful. I think I even wrote something about that experience on MUD someplace. So yes, I'm not that enthralled with these things admittedly, but if bought with full knowledge and acceptance of their limitations then life is good.
Keep in mind you'll need a constantly-on 12V outlet if you want to keep things coldish and then you'll have to keep an eye on the battery.