Wow, well done. I would be just super scared about wood in rental units. But this might be a German thing cap rates are super low here especially in the cities.
Discussion
Why are you worried about wood in rental units?
Wood liquid and tenants... there is a plant in the corner. Somebody putting to much water. Some time later you move away the furniture...
Furniture being dragged around leaving deep scratches.
In Germany we are also moving our furniture around when we move and and all of us diy (distroy it youself).
Rental yield of typically 3% means also at least 2 years of renting out only pay for the floor.
If you can rent it out to somebody for 10 years plus dead on, no problem. With switching tenants I am honestly scared of having to sand / renewable to flow every 2 years. And I am thinking about my apartment here which I will be renting out in a couple of years...