To be fair, there is actually plenty of street parking near WIN Stadium - we were there early for the Origin (just caught the last 10 mins or so of the u/20s), and there was still heaps of parking in the free multi-storey council carpark at that point. You want to look at the side streets on the opposite side of Corrimal Street, not on the stadium side where there's not much parking at the best of times.
There are also more toilets (not portables) at the back of the GA hill, it's a bit like Brookie in that sense - find the amenities not as many people know about and you're all good.
Also not sure what people mean about not being allowed to walk around inside the GA areas - I got up and went for a wander several times, and we shifted where we were sitting at least twice to make room for more friends turning up. Yes, there's a fence between the alcohol/no alcohol areas of the hill, but you only have to go down either the front or back of the hill and use the pathways to go around.
I hadn't been to WIN in years after my nephew (5 or 6 at the time) was verbally abused by drunks and had beer cans thrown at him at a Saturday night game. Security did nothing about them, even though we were sitting in the 'alcohol free zone', and we ended up leaving before the end of the game because it just wasn't safe. No issues at all yesterday, the crowd around us were fine and the security guard nearest to us even thanked us for putting all our rubbish in a plastic bag to make it easier for the cleaning staff to collect.
Apart from the main game itself, our group actually had a really pleasant afternoon.