Thanks for everybody's responses. Looks like this interior fan is a hit or miss. Some like 'em, some don't.
Again, our frig works well. It came from the factory with a chimney fan that's thermostatically controlled, plus the top vent is on the roof (vs. a less efficient side vent). Was able to sustain 40 degrees in 112 degree heat. Up to about 100 degrees it kept temps around 32-34 degrees degrees.
The frig on our previous toy hauler had a difficult time staying below 40 degrees when ambient temps got above 85-90. Discovered the factory didn't install the rear baffle correctly. Had to move it 2-3 inches closer. That helped. What really go it working well was the installation of two computer fans near the upper coils (in the chimney area).
Anyhow, we'll probably give this interior fan on eBay a try. We're ok with taking a $15 gamble. Would be nice if we can improve our frig's performance in extreme temps.