there's a couple of things you could do @Dara78
The most obvious one is to limit your calendar so guests can only book 3 months in advance - or 6 months in advance - whatever, so the special holidays don't creep up on you. Of course you have the option to manually over ride whatever smart pricing for any dates at all - even when I had my calendar set up for 6 months in advance i still entered the prices for peak season 9 months in advance, so when the calendar did open, they price was already set.
Or you could turn off smart pricing and set a minimum you're happy with in off season and increase it at peak season. The trick is to be vigilant with your calendar.
I don't quite understand your problem with the 7 day issue. You have a 7 day minimum, but you don't want people staying longer than 7 days either? Can't you enter that into your maximum stay setting?
Hope this helps