Our experience with obstructed view rooms is that the obstruction rarely comes right up to the window and covers it completely. If it is a lifeboat there is some shape to the boat and some space between it and the window that allows light in. If it is a stairway or partition, there would normally be enough open deck to walk on so again some light would get in.
A trick many people use in inside cabins is to leave the TV tuned to the bow camera channel and pretend it is a window! I don't know if that would work for you or not. During the day, you would get the effect of sunlight.
Only you know how serious your claustrophobia is. The honest fact is that many hotel rooms fit what would be considered an "obstructed" view on a ship. If looking out your hotel window at the wall next door does not bother you, perhaps you would be OK. I think there is also a fairly large psychological effect from simply knowing you can't get off the ship!
Have a GREAT cruise!