I just did this mod today. My Dometic is in the super slide and the single factory fan was a bit on the noisy side. Not obnoxiously loud but loud enough to be annoying when watching TV on low volume or reading.
I replaced the fan with 2 larger fans which are super quiet and flow more air. Here's a
clicky to the fan on Amazon.
I also added some Reflectix across and over the top of the upper coil fins to direct air from the fans out the upper vent. There is a void above the coils that traps hot air so very little if any flowing air would get out of the vent.
Outside temp is 91F right now with the slide in the direct sun. Freezer temp is 20F and fridge is 41F. Decent cooling performance with the heat soak.