The enclosure is only compliant as long as there is no non-compliant enclosure placed behind it.
In this respect, I do not see the exercise ... as applicable here. I suspect that the official information will indicate: "not at all in the triangle," and the simple height as the distance behind it would then be considered appropriate.
Why should that be the case? I am not aware of any regulation stating that no clearance areas are allowed in visibility triangles.
In my opinion, that also makes little sense if you look at the purpose of visibility triangles. Either they are sufficient, then there is no reason to impose further restrictions outside of them, or they are not sufficient, in which case they would need to be enlarged. But as already said, just ask the authority and that's that. Then you have certainty.
For unjustified regulations, I saw and still see it the same way – but "also with a smiling eye": in this sense, any excessive regulation can also be a welcome occasion to drag a development plan before the judge.
If you want to waste your time with court proceedings with uncertain outcomes, you can do that. For me, that's simply too stupid... and being right and winning a case are two different things – even in German courts.
As an example: Requirement in the development plan for shed roofs with a max. of 16 degrees AND roofing with tiles/slates in red to reddish-brown colors.
1. Standard roof pitch for tile roofing is at least 20 degrees
2. A builder didn't care about that, made a 7-degree roof pitch with anthracite-colored roof tiles. The municipality asks him to reconsider. He: no! Subsequently, the municipality requests the district office for an order to remove it. The district office conducts an on-site inspection, concludes that this is not appropriate *) and recommends the municipality to tolerate this deviation because they would probably lose in court. The head of the building authority passes the recommendation on to the municipal council and also supports it. The municipal council says no and continues to annoy its citizen... and now?
*) Reason: The municipality believes the village character would be affected by different roof colors. The problem is that with a 7-degree roof pitch hardly any of the roof area is visible, and two streets away (different development plan) black roof tiles can be found on a 50-degree gable roof. This is also the district office's argument.
Sorry, this is off-topic.