I like putting the trailer ball on the mower for light tongue loads. I did put one on top of my box blade and use it that way for a while, but then i added weight to the box blade itself and any more from a trailer just becomes too much for my tiny b6100's 3pt (8200 has a backhoe on it full time), so i removed it.
As far as not being able to see the trailer ball if its 'down in the bucket' keep in mind you can curl the bucket back a long ways before you exceed the angle the ball can slide into the coupler at. So you may be able to curl the bucket back enough to see the ball, and still get it up into the coupler at that angle. It does depend on whether your bucket edge starts hitting the trailer before you can see the ball, so it's a 'maybe'.
I HIGHLY recommend the ATV hitch from Harbor Freight for these 'add a hitch to a tractor projects'. You can't get anything close to this for $11 unless you build it yourself, and right now it's on sale for $9!
ATV Hitch
Also, I have found that by mounting it 'backwards' and leaving the attachment hole empty (weld it on), most of my drawbars will still fit in it (some hit the thick bottom rail before the pinhole lines up) and you also have a 'clevis hole' if you pull anything with a clevis. Honestly if i buzzed off about the first 1/4" of metal on that thick bottom piece, i think ALL my drawbars would fit in it backwards.