As long as the traveller car is low on friction it should be OK to move by pulling, if you let the tracks get dirty then it can be tough to move it when the sail is loaded. You should be able to adjust it on the move as it is a good way to depower if the wind gets up. Alot of helms have their crews adjusting the traveller.

As for a "short" or "long" piece of rope, just do as everyone else does and have the end of the mainsheet feeding into the traveller system so it's a continuous loop, then when you're on the wire with the mainsheet in hand, you can also control the traveller.