I hand sanded down the neck of my Strat, eons ago. (It was one of three guitars I used at the time, so I did not miss it while it was out of commission.) I was honestly afraid of using a belt sander or drill with a flex plate sanding base, as I feared I'd take off more in one area than another. So basically what I did was remove the neck, got some heavy grit sandpaper to start (to remove the finish-as time wore on, I switched to a lesser grade sandpaper) and sat on the back porch during baseball season. I'd drink beer, watch a game or two and sand away. Over several weekends during 162 games, I managed to remove the finish and take the neck down roughly 1/8 of an inch at the sides to almost 1/4 at the back.
I do not recommend this practice to anyone
, as it was a fairly reckless manner to do things. I did not measure or truly plan it out, I merely kept sanding until I liked the overall feel of the neck. And as stated, it was a time consuming process. I did not finish or seal it whatsoever, so over time my hand's sweat seeped into the neck, truly giving the guitar character.
Since then, I can not imagine
playing a finished neck. Perhaps the connection to baseball is significant, as the feel is
much like that of a good bat.
All I can recommend is that you are patient and extremely careful with the process. (I was very lucky I didn't ruin the damned thing) Be sure to plan out what you'd like to accomplish, and also take into consideration the purchase of an unfinished replacement neck, which would also save you considerable time and effort. Besides, if you screw up the original, you'll need one.