For a scale model I would go with the scale wing incidence, which is usually a little positive relative to a datum line that parallels the fuse. Otherwise the plane has to fly at a bit of a positive angle, which is draggier, and it affects the angle at which the plane lands. Also, wing incidence relative to the fuse is quite noticeable, so you run the risk of marring the look of the plane if you change it.

For the stab, you're taking a guess at what will work without having to trim the elevator. Generally, same incidence as the wing seems to be the best bet. Even with the stab above the wing, the air flow around and behind the wing probably gets diverted downward enough that the stab is going to be a little bit negative relative to the air flow.

If the wing is a little positive relative to the fuse, then if the engine is at zero relative to the fuse, it is negative relative to the wing, and you have a bit of downthrust even if it doesn't look like it. Downthrust and right thrust are guesses, and I'm sure you won't hurt anything with a degree of each.

Jim