Bro, I went to Gilgit, Hunza to Khunjerab Pass from 7th July to 11th July 2016. I drove from Islamabad to Gilgit, only making small stops for food or restroom and it took me 18 hours Approx (Including rush in Naran, Abbotabad & Havelian). I see nothing wrong with your plan, but I would advise that you do not stop and stay at gilgit as it would be a waste of time and money both. Gilgit is quite hot during day times with not much to see. I would suggest that you make another 1 hour & 45 mins drive to hunza directly from gilgit to save yourself a day or two. 80% of the road from islamabad to Khunjerab pass is excellent (Specially road beyond Raikot bridge to Khunjerab pass).
Use Babusar top route for returning to islamabad as it will save you 3 hours minimum as compared to silk route and the road conditions are much better at babusar road as compared to silk route (Its a word of mouth).
Plus, DO keep a Fuel can of atleast 20 liters or more and keep it filled. because of huge amount of visitors the supply of fuel fell short of demand and people had to stand in long ques at selected fuel pumps to get petrol. You never know when it might come in handy.
If you need anyother information feel free to ask. ![:slight_smile: :slight_smile:](/forums/images/emoji///apple/slight_smile.png?v=3)