During the last weeks I was working to refine the visual setup. With one projector it was not possible to achieve the wanted result.
Therefore I bought another Optoma GT1080 Projector and built a ceiling construction where the projectors are mounted.
After hours of understanding the Immersive Display Pro Software and a help from a friend we got the following result.
Not bad. With the applied blending you can not see the overlapped projected pictures. Its not perfect right now, finetuning is still needed, but a good way to go.