The good news is that your RV fridge has the ability to get cold!

Your RV fridge operates differently from your "home" fridge, it is designed to keep your food cold. However, it is not designed with excess cooling capacity that will allow it to cool itself down very quickly if it gets warm, it is more of a slow cooling versus the quick coldness of your home fridge.

Consequently, you need to do everything you can to help it get cold and stay cold.

First off, your RV fridge works off of heat and air flow. The coolant inside your fridge is heated at the bottom of the fridge and a set of cooling fins at the top of the fridge get hot when the hot coolant moves through the system. Those (now hot) fins at the top of the fridge cause cooler air to be "sucked" up from the outside bottom vent ( behind your refrigerator) and get exhausted out of the top vent, this creates a "chimney" effect which cools the fins which allows the coolant to cool your fridge. Obviously, the cooling of the fins is effected by the outside air temperature.

So, what can we do to help the refrigerator work as effectively as possible?

Inspect the back of your fridge, remove the cover(s) and be certain the area is clean and there is nothing blocking air flow across the fins at the top of the "chimney".

Inspect the drain hose to ensure it is not blocked, when re-installing the vent cover ensure that the drain hose is not running "straight down", but, that it has an "S" bend in it which will trap water inside the hose (similar to the "P" trap on your kitchen sink) before draining to the outside of the trailer, this will keep warm outside air from getting inside your fridge through the drain pipe. Also, be certain that your condensate pan is installed in the fridge and that it is allowing the water to flow into the drain pipe (mine had been installed backwards).

Another thing to check is the "Thermistor", it's a white piece, 3 to 4 inches long,  that is clipped to the fins on the inside of the fridge. The thermistor acts as a thermostat for your fridge, it should be clipped to the right most fin inside the fridge. To adjust the temperature in your fridge, move the thermistor up (for colder) and down (for warmer).

Start with running the fridge for several hours before you leave on your trip, you want that fridge to be as cold as possible before you put your food into it. Next, only put cold food into the fridge, don't load in a six pack of sodas (or beer) from your warm pantry, put them in the home fridge before you load up the camper. If you are on a trip and have to load warm sodas in the fridge, load them up at night when the outside temps are coolest.

Also, try to keep the door closed as much as possible, open the door and get every thing out you will need for that meal, don't open it seven or eight times while you are cooking, once or twice should suffice.

Finally, operate your fridge during the hot part of the day on whichever fuel it works best on, if it operates best on propane, then run it on propane during the middle of the day and on electricity the rest of the time.

I would suggest pulling your Scamp to the house and running the fridge for a full day and checking the temps every hour or two with the fridge empty to determine how well the fridge is working, then, the next day load it full of warm beer (or soda, or water) to see how well it can operate full.

Used to take my 13 Scamp fridge about 6 hours the night before to get to temp. Mine really only performed well on propane, so I never ran it on anything but propane. 20lb tank would last almost a month running the fridge only on propane and any cooking so not a big deal to leave it on propane. They also have 12v refrigerator vent fans that mount behind the fridge and increase air flow which can improve performance. I'll look for a link to the product.

Having it checked over by an RV fridge repair facility might be in order if none of this helps.