My guess is the 8 is a hold over from filters being used a "clear" lens covers.
Being in AK, you've probably never seen sunlight rays strong/bright enough to warrant a 128. ;)
In future, could be used for controller-less selfie like flight (like the Neo has). The button is located in a position where you could press it conveniently whilst hand launching with the camera facing you (again, like the Neo).
Apparently you have not done too much exploring in the red rock country of the southwest. Many roads go through canyons, not all are the very tall and narrow slot canyons you may be envisioning. Some roads are along the bottom edges of tall...
Sport mode only turns off horizontal sensors. The bottom sensor is still active and will cause it to gain altitude if approached from the bottom while in hover. You can turn off all sensors in the menu and would be safer than sport mode.