misconceptions...
"First, I found out I am not allowed to land at Munich International as a GA aircraft"
There is a GA terminal and you could land there - long term myth that one cannot. You h´may not want due to cost ;-) expect 200 EUR/pop and long hlding until they can fit you in
If you have to work Munich East, the Augsburg EDMA ist still good, just take a high speed train. Someone pointed out, pretty fast and comfortable.
Mühldorf EDMY is also good and has trains to Munich East railway station.
Oberschleissheim has a number of allowed flight movements. If you it still fits, it is a good place for a visitor.
Also depends if you want to come/go often or just once and park....
Good luck!