Allianz covers short term lets for up to 12 people. I am similiar to the OP, I also do short term lets in a house in very tourist area near the cliffs of mohair. I also make up to 1000 euro a week in peak season, 5 bedrooms. I phoned my local council earlier in the year and a lady said although I should apply for planning, it's not currently being enforced, so for now I need do nothing and just carry on with what I am doing. Her words! I will not rent out my lovely holiday house on a long term basis until such time I have a guarantee that a non paying tennent can be kicked out within a week or two of non payment and that also they are liable for any damage done to the property. For now booking.com and Airbnb all the way!
Please note, a tremendous amount of work is involved in this venture, keeping a spotless house, endless laundry, breakfast, meet and greet,and up to 14 hour working days. In addition half the year I am practically empty.