I wanted to follow up on this. Lagering these in the bottle has made a huge difference. The hop harshness has faded away, and it is now a damn good beer. My friend's wife, who doesn't usually like IPA's, even remarked "maybe I only like the strong ones" after trying this. I wouldn't use this hop blend again next time (the hop character is still a bit muddled and the Nelson is still a bit overpowering to me), but I will definitely plug different hops in and give this recipe another go.
Lesson learned - lagering can possibly save an overly harsh IIPA