Mosin, your verbal description reveals a totally inadequate shooting range.
Your constructed bullet trap is too low, and contains rocks. 20 yards (60 feet) of woods is nothing. That 5 foot bank up to the road is only 2 feet higher than your constructed trap. It's at a 70 degree angle. You are relying on 'permission' to keep others from wandering into the impact area downrange and on some kind of providence they would not be hit, should they do so. Tell us, what is your safety plan when someone on the road stops to let their dog go down the bank, or has to change a tire? Can you even see through the brush? Brush, by the way, does not stop bullets. It does deflect them.
A few days ago you were asking what was an acceptable age for you to shoot by yourself, unsupervised. Based on your absolute certainty that your inadequate shooting range is actually safe, I would say you are definitely not old enough to be trusted with a high-powered rifle.
The fact that there is a PUBLIC ROAD immediately behind your target is your clue that you cannot shoot there. Period. No discussion.
Bottom line, you cannot 'make it safe' without serious earth moving and fencing, and even then the PUBLIC ROAD will still be there, waiting for just one errant round. Find another place to shoot.