I've got a 2003 266CCR with an 8.1L/Bravo 3 and love it. The 266 does NOT have much bow rise when coming up on plane and takes rough water very well.
Any 26' boat with 10 adults on board is going to be sluggish handling and IMO overloaded. I would also think that the 5.7L would be the very minimum engine size for this boat. The dual prop is a good choice.
I would suggest a water trial to see if the 5.7L will handle the load and type boating that you want to do. For pulling tubes and skiiers with only 2-3 in the boat it should be OK. Some one on the Crownline owners forum (
www.crownline.com) may be able to provide you with more info.