I did this in a novel I wrote, actually. I assigned TLA 'names' based on their job (ENG, PIL, etc), and any time a gender would normally be referenced in the text I used XXX - both for easy searching. I got about 70% of the way through when my beta readers rebelled - they absolutely HAD TO KNOW what gender everybody was. Sigh.
But by this time the characters' personalities and speech patterns were well established, so I flipped a coin for each one, and continued onward. I'll probably do this again some day and just ignore the beta readers.
Empire of the Petal Throne. It's just so wonderfully strange. Also very fond of Traveller, because where else can you die during character creation?