[Freddy]

Ferdinando, you're absolutely right, I know very well the cost of the space in a publication and how much you have to work to get as much as possible between data and photos without affecting the text and at the same time limiting costs as much as possible.. Among other things, disgracefully, I am also chief editor of a journal of historical studies.
It is also true that too much attention has been put to the place where the picture was taken but there was a hope that this would, at least a little, help in identifying the unit.
You say that we know for sure that Golding visited Villafranca but there is a photo, exactly n. 101 of Album 1 whose caption says "Udine 3 sqd" even though, unfortunately, is the only one in all three albums, that names this location.

Marc, this is pure archaeological methodology. Wishing we could joke about "Dendrology". This is what can be defined as an interdisciplinary research.
Well, jokes aside, I must admit that you are right, in fact it really seems the typical vegetation of my area but, at this point, I cannot imagine where to search for an airfield with similar characteristics.
Unfortunately I haven't the publications to which you refer but certainly an aircraft so well preserved would not have escaped the attention and then it would have been recorded in a FIU report.
In order not to discard anything I also tried to see if in Verona Villafranca there could be a bank of that size but I couldn't find any unless it have been removed after the war and this is also possible.
It's almost certain that a bank of that size might be only along a river quite large and important.
In my area embankments like this can only be found along the rivers Tagliamento, Isonzo and Torre. We can exclude that it could be a road or a railway embankment since the upper edge appears to be grassy. On the other hand, beyond it there are trees and this is a feature quite common along the rivers sides as the strip of land between the bank and the river is rarely cultivated because of seasonal flooding.
The only place that could cater to those assumptions could be Maniago since the landing ground was very close to the river Tagliamento and consequently to its embankments. After the war and until the '90s the old airport was used as a shooting range as you can see at the coordinates 46 ° 6'57 .17 "N 12 ° 43'23 .91" E.
Unfortunately, the other photo of the plane, the 259, does not help us to understand any more unless that the plane was parked in a flat area with characteristics very similar to those of the plain of Friuli.
In the background, behind the plane and just over the white 3, I think I can glimpse something like another plane, but I could be wrong.
It is clear too, but this is irrelevant, that this photo was taken at a later time than the other because the panel to the right of "white 3" had been removed. (Ferdinando, it is the same plane.)

The presence of the aircraft could be explained with an emergency landing after being hit in aerial combat. The position of the flaps, set in the landing position and then not retracted, could suggest this hypothesis. What you see to the right of the black cross would seem to be a hole made by a 20 mm bullet shot from behind and does not seem to be compatible with holes produced by a strafing when the aircraft is on the ground. The other holes seem to have been caused by splinters of an explosive charge placed inside the cabin to destroy the plane before the German retreat. Obviously these are only hypotheses.

With regard to the Werknummer, I tried to manipulate the photo, darkening, increasing the contrast, etc.. On the fixed part of the tail rudder is possible to glimpse only the lower part of the sixth number, which is semicircular. This would restrict the field to the following numbers, 0, 3, 5, 6, 8 and 9. From these, as we have seen, are to be excluded 3 and 8 so remain 0, 5, 6 and 9.
I know this does not help very much but it's anyway something to work on.