While bcp's solution certainly looks strong and effective, there are simpler ways of securing your receiver. I have one from Titan that looks identical to yours.
First, the advantage of putting it on the loader bucket is that you can adjust the height without using a riser under the ball. Just use the loader joystick. It works nicely for hooking up and unhooking the trailer, as well as for keeping the trailer tongue level while navigating uneven ground. You really should not need to brace the receiver back diagonally. That's overkill.
You need to look at two things. The first is the side view. You might need to weld or epoxy or bolt a spacer to the receiver somewhere in that slot area, so that the receiver fits more snugly to the edge of the bucket. This will make the clamp more effective.
The second thing is to keep the receiver from rotating side to side at the bucket edge. If it rotates like that, eventually it will loosen the clamp. I fortunately keep a Piranha toothbar on the bucket, and the receiver is stabilized against side-to-side movement by the teeth. I did have to weld on a bolt to the receiver as a sort of shim to make the fit more snug. You could instead weld a piece of angle iron or c-channel onto the receiver to bear against the bucket edge to prevent rotation. You might even be able to stabilize it by putting 2 c- clamps on the bucket edge-- one on each side of the receiver, to block it from rotating. I tried to avoid drilling extra holes in the bucket itself.
So basically you need to analyze how it's moving, and then improvise a few common-sense fixes to prevent those movements. I found that my first attempts were too elaborate, and simpler was better.
