Despite having to wait for immi and customs during busy times, and after getting bags off the carousel, esp for int flights, its one of the only other 2 airports, that is linked, and easy to walk between, ADL which has 1 VAi flight to DPS, and PER, which does only the Cocos/Christmas Island flight, and MEL.
Without considering plane hold bag, it can be very fast if you do HLO for MEL, if your int flight arr outside of busy times, and you don't get picked to have all your travel possessions checked.
I only fly HLO and have done MEL int arr several times, its an easy walk to T1/T3-T4, once you have got all your items out into the open area, ie, past immi and customs.
If you must have plane hold bags because the SO said so, don't argue, just say, yes dear! in an exasperated tone, and bear with it.
Its only about a 15 min walk to get from T2 to T3 at MEL, so its not that far.
If you have to buy a rev tix, do that, there are quite a lot of VAd flights MEL - BNE.
Edit: not to mention, its (your plan) is on a separate PNR, so if anything goes wrong, you are on your own.
So, leave a connection of 2.5 hours as mentioned above, if you end up early at bag drop at T3, you can then ask if there is any chance of getting onto an early flight, better than missing out due to very short connection time.
VA is also desperate for $, and the J fares for now, are quite reasonable.