Maple also being a closed-grain wood doesn't need much sanding. If you use water to stain, my experience is between each coat, just use 0000 steel wool to knock down the grain. When I did my Starcaster I didn't use anything but 0000 once I started using the wipe on poly. you could also use 600 grit.

A tip is, sand with the grain, which on a maple veneer or cap guitar, across the body.