Update: Ungeared my setup!
After some trouble with a cold fused alu prop to the stainless steel shaft, I had to destroy parts of the geared motor pod. It worked well but was a bit long and heavy. I also did not want to bother about water ingress into the pod any longer, therefore I went for a 63100 run wet.
coated stator and rotor with epoxy
Also replaced the ESC, the Flier went up in smoke due to water ingress. The new one is a HGL-TECH 75200 and works well so far.
Changed the entry point of the phase wires, they enter from the top with cable glands, now the box is waterproof.
For the prop I first used a printed pla+ 2 blade prop from @V_S, it worked well. Now I use a Flite prop which is more robust.
thanks @Toto44 for the prop adapter