Strange "pink stuff" freezing problem

Typically in January we have extended periods of temps that range from 0 to -20 at night. I've had a handful of RVs and it's easy for low points in the PEX plumbing to hold water which can dilute anti freeze quickly. As others have suggested, I blow out all the lines with air, run anti freeze through until it comes out pink at all terminations, then proceed to blow out the anti freeze and leave all faucets in the open position. After, I dump some in the P-traps and call it good. No issues ever.