It's certainly possible, but takes a lot of work. I secured two BF tickets LAX-DPS return with a HNL stopover. I started calling 331 days out and secured seats as close to the desired fligths/times as possible. I then called back daily checking as things opened up. After about six months, everything settled in.

The best tip I can give you is to book the tickets on separate itineraries so you can take advantage of one open seat---if you stay on the same itinerary, you have to have two seats in each cabin simultaneously, which is much less likely.

Also, make sure you check for availability all the way through and hop-by-hop. For example, I was able to book CO 1 all the way through (IAH-GUM) but not just HNL-GUM; conversely I wasn't able to book the island hopper GUM-HNL, but could book it GUM-MAJ/MAJ-HNL.

Of course, my wife pointed out that if I counted the number of hours I spent on the phone checking for availability, we might has well have paid for the BF seats, but what's the fun in that?