Being open is OK, you can see Federer or Blake executing these days this way, Blake more.
But I am not sure you mean it that way.
You can see them establishing the open platform with the left foot placed to the left of the right foot, not behind it, both feet facing with the toes more towards the court, not with the toes parallel to the baseline (as in the classical close stance 1HBH), and with body facing more the court.
Also 45 degrees would be fine, IMO.
But your description on the foot movement is not that clear.
Which is your front foot, the right, here? Just to eliminate confusions.
Do you mean advancing your right foot more into the court in the final platform stance for the CC, while still keeping it in front of the left foot? I think that's fine.
To me the most important thing is the shoulder line. It must be kept relatively stable towards the target, which is here CC, while the arm pivots at the shoulder. I.e. don't overrotate the shoulders.
Also, the control of the ball during the contact line and the followthrough.
Now the position of the legs might impede you from turning your torso/shoulders during the preparation, thus this should be a concern.
I'd say that IMO the classical position with the toes pointing parallel to the baseline seems to be the most versatile one, you can go both DTL and CC. While from yours you can go mostly CC, I think.