Is it proper to hand out gospel tracts on Halloween? Yes. I’d say it is a precedent started way back in 1517 by Luther himself.
Today, the 31 of October, marks the day Martin Luther nailed his 95 Thesis on the door of a church in Germany. His goal was to spark scholarly debate within the Roman Catholic church. Instead, it started the Protestant Reformation. Now, in reality it is probably coincidence that his nailing the door happened on Halloween since I don’t think Halloween was celebrated in Europe then.
So if the effects of his one paper can still be felt nearly 500 years later, consider what effect your tract may have upon a hungry soul? Granted, many of them likely wind up in the burn pile, but if just one makes a child (or parent even) curious about the Gospel enough to find out more, it was worth the effort. So while I don’t believe Halloween is a holiday Christians should celebrate, rather than simply turning off your porch light, spread some Light.