2 hours is a long time.
There are several things that come to mind.
Run the engine FAT. Your going to be pushing it for a long time.
These races are more about who chan go the distance. Don't worry about keeping up with the fast laps, chances are they wont make it through the race. The first 1.75 hours should be a Sunday drive in the park. Its not unusual for only 1-2 RCs to go the distance. Its more about who has the most spare parts and the fastest pit crew. Check all your screws.
Lots of extra parts. Pit time will kill you. If something brakes, have a module ready to slap on. I say a module because its much quicker to replace an entire front corner than it is to replace a hub carrier. Have your buds repair the module and make it ready incase it needs to be replaced again. Pit speed is important. Check all your screws.
Batteries, Have TX and RX Batteries charged and ready. Replace them every time you have to shut down for repair and at a minimum of every.5-.45 minutes. Check all your screws.
Glow plugs, You will be running rich so you will want to replace the plug every time you shut the engine off and every time you change the batteries. Check all your screws.
Endurance races are just that, endurance. If you keep your track speed and pit time down you will have a better chance of making it through the day. Did I say Check all your screws.
Have fun.