Is there a way to move the HUD texture ahead, lets say... 20ft and enlarge it, so it would be semi-collimated ?
That would require updating the 3d model, and it's not something we can do now.
However, we used that method with the Phantom gunsight, to give the illusion of being collimated, it would need to be moved way more than 20 ft, don't recall exactly how it was on the Phantom, but was quite far.
There are also issues with that method: there's no 3d clipping so, if you moved your head sideways in the Phantom, the gunsight would still appear, hovering in the air in front of you, instead of being clipped to the hud glass.
The real solution would have been leaving the hud as it is now, and collimating via software but, unfortunately, that would require knowing the actual eye position. Via Simconnect, is possible to retrieve only the default eye position (that one you get when pressing ALT+Space to reset it), and the offset calculated by the head latency simulation. There's no way to get the eye position if that has been translated from default, for example with TrackIR.
I've been asking to have this capatibility, but it didn't make it. In fact, the calibration screw we have now, it's basically a leftover of the preparation work that was done in anticipation to make the hud fully collimated, in case the ability to read the eye position would appeared.
We can only hope we'll eventually get that feature in an eventual upcoming Simconnect update, but to get advantadge of it, we'll have make another airplane that will use it.