Im not sure your getting the concept, regardless of if they are currently travelling or how they (interstate teams) are traveling, the issue with conferences is haves and have nots... and your advocating for an all sydney only conference, and the rest, who'll have to travel long flights more often than the conf who'll won't... this creates a rift and an unfair bias, where right now as one unified competition, its more of a stiff shit situation, but if you intend to pool everyone that isn't sydney in one conference, it will deter the competition, due to most marqee athletes won't want to travel as much, thus boosting the sydney clubs chances at acquiring them...
The only way to split the current setup of clubs is straight thru the middle of Sydney , then add the nearest interstate teams to it... like I've said many posts before, north/south divide that goes straight thru "homebush stadium" as its centre, any club north of the M4 plays for the northern conference, any club south of the M4, southern conference...
As for wests tigers since they are both north in leichardt and south in campbelltown, but having concord as their base makes them just in the north, aswell as a possible expansion in a Perth team, and Adelaide or Nz2 in the South etc