Exterior wall box rotated 45 degrees off

I have an existing circular surface mount box that was mounted years ago such that the four screw holes are at 12-3-6-9 'O' clock positions.

<img src="https://i.postimg.cc/MGVhSyJg/slbox.jpg" width="432" height="576"/>

Also note that the box is very near the soffit. This creates a problem as the wall mount Eaton motion security light that I just bought online has 4 mounting screws at the 1:30, 4:30, 7:30 and 10:30 positions.

This means if I want to mount this I have to rotate the lights 45 degrees. Normally this is not a big issue because these lights have jam nuts and swivels so you can turn and tilt it, but in my case the light when rotated hits the soffit.

I know they sell one of these round adapter plates which allows you to mount through a center hole...but I specifically bought these with 4 mounting holes to give it a good weather seal.

The box is embedded in one inch of stucco over concrete block, or else I would have freed it and rotated it properly.

Right now my plan is to just mount another identical box below it with a short piece of pipe rotated the way the lights need it. Is there a better idea (except for getting a different fixture)?

 

Hard to tell from the picture but it does look like at least one screw is holding the box.
I would remove that and if there is another one near the bottom.
Then try rotating the box.
It looks round so you may be able to rotate it to the position you need. without damaging the stucco.

You may also have to unscrew the ground screw as it may be protruding past the back side of the box.