What do you all use to keep your traps from freezing solid? Should I purchase some de-icer salt or should I look towards Propylene Glycol or something else?

Wax dirt is my frist choice.

Glycol works down to a certain temp., for me at least, but now I just premix regular salt w/ dirt and peat at home... it works down as low as our temps get here in DE. 2 lbs for a buck at Dollar Tree...

X2

Wax paper under trap with waxed dirt. bed trap and cover with wax dirt. Don't make the pan the low spot as water will sit there and freeze. We have been having some terrible weather here and my traps where working and caught two cats. I try to make the sets before a small snow storm and leave the dirt exposed and let mother nature cover them with the fluffy snow.

Just remember if you go the salt or (calcium chloride which is even more corrosive) method, then you must be sure to clean up your equip. because rust will be fast. That was where I liked painted traps. With salt your bunny rabbit catch may go up and many sprung traps from deer.

Salt only works down to a certain temp, it's highly corrosive to steel, but if you have nothing else it is an option. As mention its very attractive to other animals.
Waxed dirt is my preference, ot if average temps stay well below zero even just plain bone dry dirt works OK too. Any moisture in it and it freezes. Bone dry dirt will take on moisture from air though.
Cover hulls or completely dried peat works. Those too will crust over in couple days if moisture in air. A little set maintenance goes a LONG ways when fighting freeze thaw conditions.
Jim