Second testing day !
Unfortunately the LiDAR data we use is not precise enough to determine the density of the vegetation along a path. We realized that moving from a meter could make the percentage of delivered messages from 100-80% to 0-20%. Because our transmission tests are performed over different frequencies, we observed that multipath-fading was not very present in this forest environment. The main cause of delivery ratio drop are the obstacle (branches) that produce shadowing. To verify this assumption we performed series of measurements in different paths, from very dense to no vegetation. Answer is Line of Sight, Line of Sight, Line of Sight !
We finally marked good locations for tomorrow deployment, trying to place the repeaters as possible in Line of Sight of each others.