Not sure of the cloud point, but I did have filter plugging with ULSD at 5 degrees F. Fuel purchased in KY and treated with Pre-ULSD Stanadyne Performance Formula (was using up the last of what I had on hand). Filter began plugging and pulled to side of road, let engine idle for a few minutes and it seemed to get better. Went about 1/2 mile down road to get to a safer place to pull off and it began to plug again. Would idle just fine, added a double dose of ULSD Stanadyne PF and allowed to idle for about 15 minutes. All was well after that. Not sure if it was the Pre-ULSD Stanadyne, ULSD, or what. Pulled a sample from filter later down the road and it looked okay. No more problems, but haven't been down below 20 degrees F since.
Gary