we,ve been to eire on 9 occasions & have fished through the night on 4 seperate occasions.We didnt use bivvies though as we were staying b&b.nobody seemed over concerned fished at roosky x2 sessions & last year we stayed at woodford lodge & fished a lough near there.
Not only is it allowed but I'd positively recommend it (providing the weather's OK!) My only recommendation is that you familiarise yourself with your surroundings beforehand as it is all too easy to trip over a rock and end up headfirst in the drink! I'm off to Tarmonbarry (in between Rooskey and Lanesboro) on Friday night and I shall certainly have at least one night out on the Shannon. Good luck.