The under $200 thermoelectric coolers are better than nothing. I got sick of barely cool soda and got an Engel MRFD-015D-A for just under $400. It is actually a freezer but can be used as a refridgerator. It uses about one half the power of the cheap coolers. Coleman has a similar unit called a "Stirling Power Cooler" which I think I would buy instead these days. There are also fridges that fit the built in fridge openings in the sleeper but they can be specific to a particular model truck - plus you can't reach into them while you are driving. Some drivers have both - If I was OTR I'd do that eventually but definitely the portable first!
I have used Igloos and Colemans and have had good luck with both.
Unless you let the interior of your truck hit 80+ degrees on a regular basis for a long period of time....more than a couple of hours......you will not having any problems getting things cold and fresh.
Lunch meats will last at least 2 weeks
Fruits and veggies will last up to a week.
A little tip. When home, take a 20 oz water bottle, fill it 1/2-3/4 full and freeze it. Then place it in the cooler. This will help cool it down faster and keep it cool longer if you need to shut the truck down. When on the road just get some ice from the fountain dispenser, put it in a double zip lock bag for the same result.
Finding the right trucking company is like finding the right person to marry. I really comes down to finding one whose BS you can put up with and who can put up wih yours.