The HSS guitar is not a good idea
Guitars with this type of setup may be usable, but the cons outweigh the pros.
HSS is a pickup configuration. It means humbucker/single-coil/single-coil. The way this is said is actually backwards. It should be SSH because the front of the guitar is the neck side and the rear is the bridge side, and you're supposed to label things on a guitar front-to-back and not the other way around, but whatever. The guitar industry calls it HSS.
Two things happen to almost every guitar that combines humbucker and single-coil pickups. Whether the guitar is HSS, HSH, S/H or H/S, if the two types of pickups are mixed, this crap occurs:
Problem #1 is that when you switch to the single-coil, there's a huge volume drop. It's so noticeable that you think something is wrong. There's not.
Problem #2 is that the single-coil either has too much treble response, or the humbucker doesn't have enough treble response.
What's going on here and why does this stuff happen? I'll explain.
Humbuckers have greater output than single-coil pickups. Sometimes a lot. When you switch from the humbucker to the single-coil, that's why the volume drops off a cliff.
Traditionally, guitars with single-coil pickups use a volume pot with 250K resistance. The goal of the 250K is to decrease treble since the singles have so much treble response to begin with. Guitars with humbuckers traditionally use a volume pot with 500K resistance. The goal of that one is to increase treble response since humbuckers will sound too "muddy" otherwise.
Then there's HSS. Which volume pot should be used? If the one with 250K resistance is used, the humbucker "muds" right out. If the 500K is used, the single-coil pickups produce too much treble.
Guitar makers will typically use the 500K volume pot, and that's why on HSS guitars the single-coil pickups just don't sound right. Too much treble.
But is there a solution?