Scott is correct on a few details
However the designer is responsible for setting the thrustline of the airplane ,, How the fuse presents in the air is also part of the equation and the look the designer is going for.
The designer is also reponsible to give the recomended trim and C/g location assuming he knows<G>
I have found that most of the current designs are designed by one person and another is given credit for the design, for it to have "credibility" in the Market!!
And thats where the confusion comes in ,,,,,, nobody involved with the design really knows what the proper trimming setup should be
and the guys claiming to have designed it could fly the airplane with any setup.

Having an airplane set up with no positive angle attack in the wing {as most current designs are today} causes you to fly tail heavy to get the pos. angle desiredfor the wing to create the required lift
This is where all the airplane trim problems start Snaps Suck !! Spins require low rate rudder and are very difficult to stop consistantly , left rudder Knife edge goes to the belly ,
and if you are really tail heavy right rudder knife edge goes to the Belly also,
up and down lines go the the canopy 45 up and down lines are not easy to duplicate and if you apply rudder any where you need a up elevator mix.
Engine thrust is the last thing you should address, and least effective in the overall trim process

The main wing has to create lift independant of the fuse the stab is only used to steer and stablize like the rudder
here is a quick trim method.

First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
{THIS SET UP" WILL" FLY IN THE WIND BETTER ] because the c/g is correct and the wing is always lifting pos.
I hope this helps,
please,,,,, don`t aurgue if you have not tried this set up,
However if you try it ,,,, you won`t aurgue
Bryan