Might be a long shot, but take a look at what the full J fare to/from BKK is for you. If you have a UA Club card, you can take advantage of the two-for-one BF ticket deal (buy one J ticket, get 2nd free if there is Saver J space available). May be cheaper to buy one RT full J than two W-fare RT tickets + $2500.
Plus, you would then be confirmed in J vs playing the upgrade game.