Marine wiper (3 wire, all 12v)

But in that case, i can use only the fast winding + the park winding without issue you think?

Yes that should be ok

When i apply power on the Fast winding, there's the same voltage present on the slow winding, but there's also the same voltage present on the park winding, but it comes and goes (guessing it's because of how the park winding works internally).

Am i correct in thinking this won't work with the older PDM:s then, even if i only use one of the fast/slow windings and the park winding? Can i fit a big diode and that way it's protected? Or do i need the PDM 25+ if i want to use this wiper with one of your PDM:s?