Your settings are very close to mine. The only thing different I can recommend is to calibrate your monitor.
I calibrated my monitor for brightness, gamma, color, etc. a few months after I started playing just using the Windows built-in display calibration. I was surprised how much adjustment the monitor needed for all the settings to look right. My monitor was a pretty cheap model so that may have influenced that. It made a small difference in game for spotting, but more of a difference than most of the in-game setting tweaks. The calibration for gamma involved a pretty big change in the monitor settings to match up with the gamma image Windows provided. I think the need to reduce the gamma past the in-game limits may come from uncalibrated monitors. Anything below 0.8 looks extremely dark to me.
The important bit is not to just dial up or down the contrast or brightness randomly, calibrate it against something at least. you may be surprised how out of whack the monitor might be.
I have tried with sharpen off and while I think it does help slightly with spotting I personally found it made it somewhat more difficult to ID aircraft. It was not a game changer so I have since gone back to flying with Sharpen on. Definitely try it out to see if it improves things for you.
And there are a number of visibility bugs that are still being worked out, like disappearing reflections when zooming or getting closer (same thing as far as the visibility modeling is concerned) that will hopefully be fixed. That stuff can't be countered by any setting available, so there's little point in spending hours tweaking settings for marginal returns, when your real problem might be some of those bugs.
As far as impact on spotting is concerned, from least impact to most impact IMO:
1. Landscape filter blurred - worth it, just because it doesn't seem to have a downside for me, but not a world changer
2. Sharpen off - not worth it to me because of ID problems and just general fuzziness in the game. Still, worth a try I think.
3. In-game gamma adjustment - worth it to an extent, but too low is not great either.
4. Monitor Calibration
6. Developer changes to graphics and visibility.
TL;DR - the law of diminishing returns always applies so don't spend hours upon hours tweaking; calibrate your monitor, test out your settings, and then just practice and deal with changes from the devs as they come.