I've only seen solder come through heat shrink one time since I learned about 10 years ago, and that was in a larger diameter(about 6ga) wire we were using in the wheel well of a car.
I actually solved my own problem for now, I found 4 24" extensions (I say found....they were in the trainer I thrashed..... ). I was really more concerned about interferance or anything else with making them.
Thanks for the replies guys