A couple things, first, you don't need downpressure at the hitch point of the grader, you need major weight at the wheel end, or you will pick the wheels off the ground QUICK. Notice the big concrete block on the commercial version.
Secondly, length is very important. Mine is 13'6" from hitch to center of wheels. The length of the machine does a lot to minimize washboarding.
A lot of what I did in building mine was governed by what was on the scrap pile, nothing on it came from anyplace else, other than the pin that keeps the rotation locked in place.
Don't get hyper about adjusting from the seat, because the only adjustment you tend to make once you are grading is up/down. My blade rotation is 6 positions, held in place by a pin, and the tilt angle on the blade is accomplished by a screw type load binder.
This machine has moved a lot of material, over 10 years, and hasn't had any modification. I can cut a swail in red clay with it, as long as the clay isn't baked out. The only modification I'd make, if I had the material, would be to add more weight at the wheel end.