Since every leg is a little different and the tail section isn't perfectly symmetrical, I have to basically custom fit each leg to its section of the fuselage
So I'm just using a tiny piece of sandpaper and the tip of my finger. Making them out of softwood is coming in handy, as removing material is pretty easy.
I also found that rubbing the leg up and down while applying pressure makes slightly shiny spots that I can then sand.
It's a laborious but effective process
You can soak sandpaper in warm water to make it more pliable.
I recommend trying out out with a small piece first, to get an estimate on how it holds up.