There’s plenty of videos out there showing lots of people’s own strategies for the whole level, and the defending part by the Ferris wheel towards the end.
I only wanted to add a little input on how I got past the part where you have to pick up McMillan and carry him to the helo. I had zero problems with everything before this (stayed in the left-most shack).
It was carrying him in the last 20 seconds that I simply could not complete. No matter what I did beforehand, I kept dying as soon as I picked him up, as I carried him along, or right as I entered the helo (that last one is heartbreaking).
After picking him up, I simply moved the right stick back and forth from left to right, non-stop, as I walked over to the helo. This makes Price move his field of view left to right over and over, and seemingly makes him take infinite damage. By the end, my entire screen was dark red as I went into the chopper. I had seen this method in a video from a while back, remembered it, and tried it out. I was about to give up, and was open to trying anything out when I attempted this odd method.
Not a complete solution, but just a little advice for anyone that’s stuck like I was in the last frustrating seconds of the level.