If I am reading your post correctly................
These trucks need to be run on the open road to get them into regen. Take her for a 15 to 20 mile run at 55 & above and it should prevent these issues. I seriously doubt that you could ever get the engine/exhaust hot enough to regen while plowing.
09 GMC SLT Dually
Steel Gray Metallic
All options except sunroof
Mods so far:
Tow Mirrors, Chrome Grill Overlay, Rear underseat storage, Mudflaps all corners, 20% Window tint, 6" Oval Steps, B&W Turnover Hitch, Sulastics, GM Campaign #PIT3009J
DF DRW Club Member #161