Check the JL PE fare - it can be a very small premium over economy (which is crazy because it is a better seat and comes with lounge access on both ends - but I just did this to get PE on RDU - ORD - NRT - SYD when all the LAX/SFO - SYD flights were virtually sold out since I was booking 3 days ahead of time) and looks like it would come out at about $2k/person vs. $1.95k for Y on JAL or AA for random dates next year.

If you have SPG, you can also upgrade to J on JAL flight #s for a reasonable amount of miles as long as you are in the right fare classes (the PE fare classes qualify but I didn't have enough lead time because the SPG --_> JL transfer is a slow one). That chart is here and my understanding is if BA/AS show the seats available for a J award on your flight on the day in question, you can confirm the upgrade on the spot: https://www.jal.co.jp/en/jalmile/use/jal/upgrade/

Also note that PE on JL booked with JL flight numbers earns EQD at 20% of flight distance, 150% EQMs, and 100% RDMs so if my numbers are right you should end up with $2681 EQD, 20106 EQMs, and 13404 RDMs from booking into E (lowest PE fare class) on JL