Decals covering a large area not shown anymore - or - How else to create a smooth transition to a 3D terrain?

In my Rothera scenery I created a large 3D terrain with the intention to make
the 3D cliffs along the glacier edges the way they are in real world (which
was the only way to do it without SDK access to photogrammetry technique).
Sadly the default aerial/satellite imagery in Antarctica tends to be too dark
so I needed to create a smooth transition from the darker default scenery
towards the brighter 3D model of the glacier. A “simple aerial” didn’t work
out in this case as apparently MSFS only allows one such aerial per addon
scenery. Furthermore - being locked to LOD20 for aerial imagery - it’s not
possible to cover a large area with it. So my approach was to create 3
placeholder airports around the landside perimeter of the 3D glacier that each
contain a large decal model of about 50x60 kilometers. Each showed to about
20km out from each airport center, which was the reason I created 3 of them.
Sadly these large decals do not display anymore since the the most recent
MSFS update.
Before:

After
MSFS update: (Ignore the
differences in daylight please, but the point should become clear) Is this
something that can be fixed in the next MSFS update? It’s quite frustrating
that there no way for us to create aerial imagery on a larger area (or having
access to how photogrammetry works). Thanks! Sasa

No ideas anyone?

I usually do my aerials as separate projects works fine :).

Yes, that was another idea as well. Not as clean as I’d liked it but possible.
Not an option here though because the area just is too large to be covered by
LOD20 imagery. It’ll take weeks to process - and that simply for a smooth
blend to bypass the current limitations.