RE: CG / Landing gear relationship
Yes, Reuben, that is the case for the tricycle landing gear.
The theory supporting this is that, at landing time, when the tank is empty, the CG is in the closest to the tail position.
Then the position of the back wheels should avoid that the plane could end up in a nose up attitude, with the tail on the ground and unable to return to level by itself (due to a gust or extreme flaring).
This could happen only if the vertical line coming down from the CG touches the ground behind the wheels for that attitude.
The 0.05MAC distance is a safety factor that places the wheels beyond that critical point.
On the other hand, if that distance between the wheels and the CG is made too big, that will make the take-off rotation of the model around the back wheels too hard on the elevator, when the fuel tank is full and the CG is located toward the nose.
Note that is important to have the horizontal-vertical location of the CG.
Now, for normal horizontal attitude, it is recommended to make the nose to point down about 3 degree, in order to avoid any bouncing tendency during landing.