Maybe its just me, but I'd only do that if you feel you really have to (as in, 11pm November 30th and a million innocents will die unless you win- that measure of really have to).
My advice is that winning isn't as important as all that (I mean, what do you get for winning? Only self esteem.) As much as I hate to use the cliche, NaNo really isn't about the winning so much as the taking part, and while I'm pushing myself further, that's just to see what I can achieve- not because I must win at all costs (or at least I hope it isn't about that).
Ultimately though, what words you include is your decision in the end, and you still have most of the month to make it, you don't need to rush simply to pad your word count...