Booking the Island Hopper on a Revenue Ticket?

I am thinking about booking the Island Hopper via revenue ticket.

I found a few fares that seem to permit routing via HNL and GUM.

1) Upgrade question:
It appears that "HNL to GUM" does not allow CPU's or RPU's (nor Y,B,M upgrades for that matter). I suspect that is because the flight appears on United.com as a through fare HNL to GUM with stops (aka a "direct flight"). I am wondering, if I manage to get the HNL to GUM flight split into individual segments, will the system then permit CPU's and RPU's?

2) Splitting the HNL-GUM "direct flight"
I assume that I'd have to do the hang-up and call again feature a few times to get an agent that would split up the segments for me?

3) Assuming that I manage to split up the segments:
I'd assume that I'd be issued individual BP's for each segment. Would I need to de-plane at each stop in order to get the GA to scan my BP so that the system doesn't mark me as a "no-show" and cancel the rest of my itinerary?

I thought that you can't de-plane at KWA unless you have the right "paperwork."

4) How often does R/RN space show up on the Island Hopper?
I couldn't find any R/RN space at all. I assume that if I find R/RN space, I should try to snag it with a RPU. I suspect CPU chances aren't that great.

Thanks all!