Do you know how to solder?

If so, you could get a long roll of servo wire and use the male and female ends from 2 shorter servo extensions to make a 4-wire dual-elevator extension. The red and black are soldered together with their respective colors, with separate signal wires for each servo. In short, common power and ground and separate signal. I have done this a couple of times and it works great and makes for a neater installation.