Since I have nothing else to do, I've decided to fabricate and install a ROPS on my 6520PS. (Ok, "6520" is my own imaginary model. TECHNICALLY it's a 4020PS with a fully removable loader, which I consider to be an upgrade over a 6020. So I call it a 6520.)
Anyway, what I really want is a shade canopy. But a shade canopy mounts to your ROPS, so first things first.
The verticals are made of 2" EMT, and the horizontal is 3" EMT. I began by putting two bends in the vertical members, the first bend to conform the the slope/angle of the trailing edge of the fenders, and the next bend to turn back upward so that the member stands mostly plumb. In reality, the vertical members are angled just a bit toward the back. But it looks natural enough. The bends don't look factory at all, but I can ignore them. The truth is, if I ever do roll this machine the EMT will bend. But I think it should be strong enough to keep the tractor from rolling fully upside down, and I think it will be strong enough to at least leave a protected/sheltered pocket for the operator to crawl out from.
But the EMT has to be bolted to more than the fenders, because in case of a rollover, the fenders themselves aren't adequate to support the ROPS. The bottom end of the verticals needs to tie into something more significant. At first I intended to run a heavier pipe down to the axle and fab a clamp to go around the axle tube. But in my case, the way I built the 3 point hitch, there happens to be a u-shackle that holds the front end of the lifting arms, and I was able to drill through the back face of that u-shackle, and bolt the bottom end of my "heavy" support pipe right to that face. So in a rollover situation, the heavy pipes are securely bolted to the meat of the 3 pt. hitch, and the 3pt hitch is heavily bolted to the frame. All I'm really asking the fenders to do is prevent the ROPS from pivoting backward, and I think they'll be ok for that.
For the "heavy" support pipes, I bent some 1 1/4 schedule 40 steel pipe to around 30 degrees, and drilled a 1/2" hole into the lower end and welded a 1/2" nut inside there. A 1/2" bolt goes through the back face of the lift arm u-shackle and screws into that nut.
Then the heavy support pipe leans against the fender wall, where I drilled through the fender,the emt, and into the heavy pipe. The upper bolt hole has a 5/16 nut welded in place. There's another bolt about 8" lower down, but for that one I had to use a rivet nut, because I cant get way down in there with a welder. So two 5/16" bolts serve to clamp/sandwich the fender to the EMT to the heavy support pipe.
The final part is joining the horizontal 3" EMT to the two EMT verticals. For those kinds of joins, you can make a strong, decent looking joint by holesawing through one wall of the 3" pipe just big enough for the 2" pipe to slide through. Then you build an insert out of regular schedule 40 steel pipe that slips inside of and is welded to the 2" EMT. The top face of the insert is a hole-sawed slug from a piece of pipe, so it is outward-bowed such that it nestles against the inside wall of the 3" EMT. And from there you drill/tap/bolt that insert to the inner wall of the 3" EMT.
I intended to weld the upper joints all together after I bolted them together. But for this second I've just left them bolted together. I may weld them later, but I doubt it. In case of a rollover the strength of that joint isn't terribly critical, other than maintaining the spacing of the two verticals, and it will do that with no problem.
You can also see some extra welding around the upper end of the driver's side vertical, where I had to weld an extension onto it, because the reclaimed piece of EMT I was using was a bit too short. So I butt-joint welded on an extension, as well as a heavier inner sleeve to reinforce it there.
I'll mount some LED lights up here, and I'll either buy or build a canopy to put up here.
But that's for another day.
Bob
"Never be afraid to try something new. How hard can it be?"
let's go, it's finally time to blow. 
the flat top, little one that Ford used to have on their small tractors would look good too. 
or a barrel 