Let's face, the end of M8 just doesn't work on many, many recordings (on some it works great). I've thought about this a great deal, and here's what I would try in a studio recording situation. Starting at the second tam-tam smash (well after the chorus has cut out), I would do a separate session with just the brass, offstage brass, organ and percussion. Perhaps I would leave the woodwinds just to add some 'tang' to the organ chording. But I would definitely remove the strings and choral forces (to open up the space behind - less bodies the better).
The organ should sound a true fortissimo (as marked) and the bass drum rolls should be a solid forte (no need for fortissimo). Ideally, I would like to beef up the offstage brass from their usual numbers, and make sure that they're well in a balcony section someplace (and not behind the orchestra, which is lame). Removing the strings (and possibly the woodwinds - who needs them?) and opening up the chorus area for more resonance, should help to bring out the tam-tam smashes more clearly. With the strokes that are doubled with cymbals (the final three), I would like to switch to suspended cymbals - possibly two pairs. Using a pair of mallets on each suspended, played on opposite ends of the cymbal, should give plenty of sound. I think this would work much better with the tam-tam (especially Wuhans) than plate cymbals.
This would help bring out the organ, offstage brass and percussion without everything just turning into a sonic mush. In an effort to avoid over saturating the mikes, many recordings are trimming back on the organ. I don't like that because that's not what Mahler wrote, nor intended. Anyway, fuel for thought.