Your short section of 18G wire will have more resistance than the 14G layout wire. Check for heat in the short section while operating. The Z1000 will probably be OK. A Z4000 at 10A load may generate heat.
A long time ago, someone at my club used a banana plug harness from a RTR set to join a Z4000 with the track. I don't know the gauge of the wires but they got hot enough to melt the insulation during an hours long show.