Actually, Ottomans in 1.5 are perfectly positioned to play very aggressively without getting ruinous coalitions. Early expansion is low AE (reclaiming cores and expanding through vassals, which continues in the mid to late game (Ukraine, Persia, even Novograd if you push north, India eventually), and the fact that you are surrounded by different cultures/religions makes a strategy of moving from theatre to theatre viable, not building up too much AE in any one. Rinse and repeat.