Melting Sleepers

My soldering skills aren't really up to precision work, and anything plastic in the vicinity of the target tends to suffer from collateral melting.  Real railway modellers solder dropper wires to the sides or base of the track to get power into their layout.  I decided to solder to the rail joiners.  I'm assured by the forums that this will cause me endless problems with dodgy connections in the future.  At the moment, I'd rather have a possible future problem than the immediate disaster of sleepers forming pools of runny plastic.

I've experimented with soldering dropper wires to joiners both in situ and away from the track.  The latter is better if I want my sleepers to remain whole.