I haven't booked a 30K SWP award yet however probably will in the next week or so but mine will essentially be a GUM/Aust/GUM ticket & will only need overnight transits in Asian cities.
I just wonder whether one option would be to book (& put on hold) the itin you want with only transits in Asia so US DM are kosher with it eg the return sector may be:
GUM UA x/NRT 01 Jan TG x/BKK 02Jan SQ x/SIN 02Jan SQ SYD 02Jan
Then when you call up to pay for the ticket you could say "I just want to advise my credit card number for payment, oh & I just need to make one tiny change to one flight......can I move my UA flight GUM/NRT forward 4 days so it would still be UAxx_ GUM/NRT but now on 28Dec"?
Then hey presto NRT stopover.....maybe!
Of course you would have checked first on
www.awardtravelr.com or
www.expertflyer.com that there are "I" class seats available because making it easy for the CSR is the name of the game.