Business first on the island hopper is an easy get. At silver level on CO on a full Y fare you can generally upgrade automatically to Business First on the island hopper when you purchase the ticket. Its the IAH to HNL that you won't be able to ever get an AU on a full Y fare, you gotta use miles for any upgrade and it goes fast and furious. Same if you are going onto GUM then back down on 956. So that's the issue, get the BF into HNL or GUM. From there on out even on Silver level if you have it can generally assure you a AU.

Since I've lived in the middle of the island hopper (Kosrae) for over 10 years I've never sat in the back on a Y fare ticket even when I was only Silver level, my kids are only Silver level and they are constantly upgraded as well. If you want more info just PM me. I'm in GUM on my way to IAH now as I just stepped off 957 Island Hopper.