That graph package is flawed in regards to >-3dBFS.
Checking in the local map is quite sufficient though in my experience.
(If you want to fix the graph check this post Optimize Gain - which would you chose - #174 by wiedehopf)
Also as you have 2 stations anyway you could choose to set one of them at a gain which would lose you close in aircraft but may capture ones far away better.
Depending on the setup that may not help though if the noise is too strong.
(Increasing gain does not help receiving weaker signals because they drown in noise)
You also need to consider if you are already maxed out due to terrain 