The problem isn't how to configure Dcs to run most of the time in a satisfactory manner, I can manage that just fine. Hell, it only takes two settings, make shadows (FLAT/FLAT) and the problem is gone altogether in all situations. I'm talking with shadows maxed here, as I mentioned in the title.
I did a test with LOW-preset, only changes being setting shadows to HIGH and DEFAULT and took off in MI8. Flying treetop level in Syria map in a large forested area brings my gpu usage to 100% and then the framerate plummets and immersion is lost. This is with everything in its lowest setting, only with shadows maxed in 1080p 60hz. 2070s max temp being 68c, power limit 100%, clocks maxed - nothing out of the ordinary.
The only workaround which I've found is to disable v-sync and force max frame rate in NVCP to 60, although that results in tearing in these situations but the framerates stay higher compared to with v-sync on.
The state of the current engine this game has is one of the reasons they are currently working an overhaul which is expected to hit us in Q3 2021. I'm losing my mind here waiting for this to happen, hence I ordered a cpu replacement (5600x). I pray to the old mountain gods I don't need to upgrade my gpu for this in the current market climate.
Update forthcoming in a couple of weeks, in case this could prove beneficial to others.