I have been winterizing motorhomes for 14 years and have never had a problem with a broken pipe (knock on wood). I do what you have done with the trailer. Drain all the lines, holding tanks, water heater, remove water filter under sink and blow out all the lines. I then ad pink stuff to the holding tanks and traps. I feel running the pink stuff through the lines is OK, but overkill. I am trying a new way to winterize this year, after I retire in 30 days I plan to head south!!
John and Marion Bell
Highlands Ranch, Colorado
2013 Keystone Bullet 248RKS, 2013 Ram 1500