If it's 5 deg C, slush and the course is salted rock hard. How much colder will you wax? Are we talking (swix)violet? blue?
This is how I prepare for spring corn. I'm not sure about salted courses but Swix Glacier Wax sounds like an option as does some moly. Along with adding Swix, we're due in some Toko Moly this week, FWIW.
A coarser structure is critical in wetter snows and it may be generally better to go with a medium temp LF or HF because the medium is more durable, while the LF or HF is better in wetter conditions. Higher humidity generally indicates need for more fluoro.
I race and train on Hood. Slush and salted courses? The most straight forward deal for me so far has been Holmenkol Mt. Hood Training ski wax:
The snow doesn't need to be dirty.
So if it's 5 deg C or more you will wax yellow? I think that the salted course is killing the bases if you wax with a soft warm wax.
The point was that I would pick -overlay- based on the dirt and the free salt, and stay with the yellow WOD.
If the justifying mechanism for this is 'less free water' instead of 'sharper, finer snow', then doesn't that make a case for adding lubricant to wax instead of making the wax harder?
So instead of waxing harder you go with fluoro overlay?