That is an excellent idea for an upgrade. I built a clone of the 4shorts plow and it is solid, but it digs in way too hard all the time as there is too much weight on the blade from floating the entire FEL. As a result you have to run it manually on height, which is very sketchy, of course. Maybe not an issue on perfect surfaces, but a huge issue for me. I sold it along with the tractor to a friend and he has had that issue with it too. So he runs it manually on height too. The ability to float the lesser weight of the blade only - while allowing for down force
when you need it, is the key improvement that is needed. Hopefully your design works out and then I will copy it!

I ran into another WNY person (I grew up there) on the forum who suggested floating the blade when I was building mine. I was too far along and did not listen then. After using it, I wholeheartedly agree with him. But that sort of improvement is what happens when you get a lot of people with experience looking at an idea.
I have a build thread on here somewhere for mine if you are curious.