I built one like that a couple of years ago. I ran a brace from each side at an angle back to the face of the blade. I also made the skids on the bottom of the sides adjustable so I could start the season out with the bit off the ground to leave some snow to pack down. Problem is my farmyard is gravel, and the grassy areas to the sides have undulations. Well, there WERE some undulations, but the bit took care of a lot of them and I ended up moving rock and sod to clean up in spring. This year I'm in the process of cutting a 3/4" slot lengthwise in a piece of 2" pipe to fit ovet the bit. Securing with steel brackets to the bit bolts. Should make the bit slide over rock and sod without digging. Did this with the loader bucket 25 years ago, and it seemed to cure the digging problem.
You might want to consider this, unless you're lucky enough to have all hard surfaces to clear.
