Don't forget that the inner hard points, the ones you'd be losing, are the wet hard points, so you lose your capacity to carry drop tanks. They're also rated for the heaviest weapons load-out, too.
In all honesty, adding a wing fold to a Skyhawk is a losing proposition, with a negligible gain in reduced deck footprint being traded for considerable net loss across structural strength, weapons capacity, weight, range, agility & speed. Adding a conformal tank, say in the form of the "hump" common with A-4F's-&-beyond, would just increase the weight disadvantage.
It's a small aircraft, with a small deck footprint. So, unless your carrier is even smaller than a
Majestic, there's no real reason to make it smaller.
I'm fairly sure, they could operate from
Melbourne with their full combat load-out (or near it) but didn't unnecessarily (& I'm also fairly sure it was the condition of the deck which limited their capacity in later years - it wasn't good

).
As much as I, a Tracker Whacker, hate to say it, Ed Heinemann designed an excellent little attack fighter which is extremely difficult to improve upon.
PS: I'm not trying to be a Negative Nancy but the Skyhawk was selected by the RAN as its Fleet Air Defence fighter because it was the largest aircraft capable of performing that function successfully from the
Melbourne. The FAD role requires the fighter to have the ability to fly off the deck carrying a full fuel load, including 2 drop tanks, & a full weapons load, including guns & 2 x AIM-9 Sidewinders. The A-4G could do that.