In our last TT, we replaced a broken Dometic 6 cu ft fridge with an Avanti 7.4 cu ft apartment size fridge. We purchased it online for a little over $300 and had it shipped to us in 3 days. It was about 6" taller than the Dometic, so we took out the trim piece off the top, cut 6" off, then installed the fridge and put the trim back on. We had to rig up a closer to make sure it didn't open while going down the road, but we drilled a hole in the plastic and put in a small dowel rod which was on a short chain.
We never had a problem with it getting warm or thawing things in the 4 years we had it in the TT and we did several trips of 7-8 hour travel time. We also don't boondock, we always have some type of hookups.
This is where we purchased it.
Avanti 7.4