I just came from a long road trip from Islamabad to Gilgit, Hunza, Shindur, Kelash, and Chitral last week....
Best way to go Gilgit is not KKH, as due to repairing it will take more than 22 hours to approach Gilgit. I will suggest to go through Babusar pass , from Mansehra turn towards Naran after crossing Naran move towards Loolosir lake and then move to Gilgit 60 % road is metal and rest of it is also not that bad (as compared to KKH) but only if you are on a Jeep/SUV. You will be in Gilgit within 17 hours. if you are tired then stay in Gilgit or better move to Hunza, it will take 3 hours to approach Hunza; KKH is at its worst condition from Gilgit to China .
From Hunza to Khanjrab pass 7 hours. From China Border you can hire a jeep or use public transport for other cities.
It will take 5 days to go China and coming back with frequent stops and over night stays. And it is not that expensive.
5 persons
Accommodation and food for 7 days 20,000
Fuel from Islamabad to Khanjrab and back 19,000 (we had 1994 SURF)
DO NOT EAT FROM HOTELS use sandwiches or tin pack food (after crossing Abbottabad)
From Khanjrab onward its very Cold (take all necessary items)
Mode of transport ater Border area Public transport (in day timmings) hiring a SUVs
Border is closing in September
You will hardly get visa due to recent religious clashes in urumchi and shenzhen
(24/7)
Good Luck