The only real reason to fly lower would be to get smaller GSD data.
80/80 overlap with the gimbal tipped up 15-20 degrees taken from the ground level should be fine. The areas below ground level will get more overlap.
You can certainly supplement that data with manually flown shots. The output GSD will be that of the bulk of the input images.
Map Pilot Pro will set the speed accordingly based on your flight height and overlap settings.