Building plot in the 2nd row with a narrow driveway

I have also read this regulation with a minimum passage size of 3x3.5m, but I understood it in such a way that the passage only has to have these dimensions if it is more than 50m away from the street.

... or whatever it provides access to.

You can forget about lifting the building material or wall elements over the house. The street seems to me to be a regional thoroughfare, no one will close it for your construction.

I do not see any development behind the existing front house here - rather a potentially denser development in the course of replacing the front house.

Our building authority stated that the width of the driveway is more or less of no interest to them (and also to the fire department, who stay at the front anyway and work with hoses). The main thing is that it is developed with pedestrian/vehicle/utility rights.