Dometic has a ventilator fan kit for the RM1350 that adds 2 additional fans on the back of the refrigerator to force more air up. There's a thermostat that turns the fans on when temps are high.
Here's the fan kit info with Dometic part # and SKU #.
1 * 3108705.744 KIT, SVC DBL DR PWR VENT
SKU # 9108554165
At last year's national rally in Goshen, the Dometic rep said this kit was available as a free warranty fix for customers having trouble cooling in hot environments. When I called to get the kit the rep didn't recognize that there was a warranty program and wanted to sell me the kit, but after some calm discussion about whether Dometic refrigerators are intended to keep food from spoiling in Texas when temps are 100 degrees, they agreed to send it at no charge. I thought I might install it myself but ended up letting the dealer put it in since I had to take the rig in for other work.
But you may or may not need these fans.
Dometic says there are 3 things that must be correct for proper cooling:
1) Refrigerator has to be level. If not, the gravity flow will not be optimum. You might be able to check this with a small level placed inside the unit. I think front-to-rear leveling is most critical.
2) The heated ammonia has to be at the correct temp. Too cool or too hot can both reduce cooling. It probably takes a tech to check this, but you can run one test: see if there's any difference between running on A/C and on LP. If one mode works better, it may mean that one of the heating devices needs adjustment or replacement.
3) Airflow has to be sufficient. Fans and baffles determine the airflow. As others have said, the baffle positioning is very important.
You also want to check the door seals. If the doors aren't aligned properly or if there's a seal defect, warm air from the coach will infiltrate the refrigerator. If the freezer is cold but the refrigerator is warm, you probably have an air leak. You can test this with a dollar bill. Trap the bill halfway in and close the door. Then pull to make sure there's some drag. If no drag, you're leaking air.
ALSO, make sure the flap on the left-hand refrigerator door is rotating into position when the left door is closed. The right door seals against that flap. If the flap is binding, it may sometimes stay in the open position causing a gigantic air leak.
If you have any of these problems, the fan kit probably won't make up for them.
And if you stand in front of the refrigerator with both doors open trying to decide where to put things, or what you want to eat, nothing will fix the problem. Close the doors faster.
And if you are putting large plastic packages or bags inside so that they block air flow, you probably will still have problems.