Evaluating slopes from a picture is NOT the same as being there in person. Does the slope in the picture match the slope in your brain when you are standing there?
If so, then yes, I would back a tractor down the backside of your dam slope.
Do you have ROP? Are you going in with a bush hog?
When the ground is DRY, I have mowed steeper slopes than that. I have only gotten a booty pucker factor (BPF) on the tractor when going sideways along slopes. I think my BPF is decently calibrated since I have had it go beyond the redline when going down much steeper slopes on a min-excavator. I have tipped the excavator over (forward) several times, and caught myself on the front bucket because I knew I was right at the tip point.
It also appears to my eye that your dam slope gets LESS steep as you encounter the thick cover. I think(?) your worst case scenario would be sliding backwards and slowly bumping your bush hog against a tree. Not dangerous, but not great for the mower deck or your 3-point arms.
I would try it with my wife watching. If it triggers your BPF, or your wife's, then I would cancel the job and go back to clearing by hand.
I hope that makes sense, it is kind of hard to explain just typing on the internet.
P.S. I do like the grass cover on the part you have cleared in the foreground of your picture. It looks like some of your undesirable plants are starting to sneak back into the cleared ground. THAT is the exact stage to spray them. Some of the herbicides (for woody plants) will not harm your grass at all. Some of the broad spectrum herbicides will do minimal damage to the grass if you apply exactly according to the label instructions.
