Final review after using it.
I graded 3 miles of older gravel road for a client of ours after logging his tract. We hauled just over 500 loads of wood out at roughly 85,000-90,000 lbs per load and packed most of the gravel down into the road. The final build is roughly 1,100 lbs and my blades are set to 1/2" below plane. I will say now that 1/2" was plenty, I was concerned that I needed more, but today removed all doubts. With my tractor weighing in at 8500-9000 lbs working weight without the implement it's borderline with the heavy plane at 8' cutting width when fully loaded. CADplans was right when he said it was the hardest his tractor has worked pulling his at similar weight, LoL!. On a fresh road in 4x4 after the plane loads up it knows it's there when loaded but keeps traction unless it hits a soft spot in the road then I would just bump up the float lever a tad and keep going. After aggravating the road top layer on my second or third pass I generally kept my hand close to the float function to bump it occasionally when the plane was loaded down. I will say I generally had no problem where the road was dryer, but when the dirt had alot of moisture is where I noticed the plane really loaded up and I had to bump the float. Overall, I'm very pleased with it and how it worked. The weight for it's size definitely makes it dig in and pull instead of hop any.
I built this much quicker than I planned to but now that it's done I'm very glad I did. I have 8 acres of new grounds I had cleared for our house to be built and pasture for the horses where it'll get it's next workout.
Oh, if anyone builds something similar in weight and size in the future, go with slightly taller sides. I would say 18" minimum. When it hits dirt with more moisture it doesn't flow near as well & even with plenty of clearance it still backs up towards the tractor and hits my top supports that are 12.5" from the blade slowing it from flowing over.