We went from Brisbane to Moree (probably about 8 hours with stops) for a funeral when DS was 4 months old. It was the dead of summer too.

It actually went really well. I was driving (DH doesn't drive) and whenever Toby needed to feed we just stopped and I fed him, put him back in his seat and off we went again. Definitely nice and easy to be breastfeeding at times like that. I was dreading it too but it was actually really easy...we left our then 2yo with my mother though because we thought it was a bit ambitious to take the two of them lol.