Here is the way I interpret this, and please correct me if I am wrong but here is my take,
If you are fishing a lake and under the "additional rules" for that lake it does NOT specify anything regarding steelhead then you can keep 2 trout over the 20" mark the other 3 trout must be under 20" and above the minimum. In some cases like Lake Sammamish during certain times you have to release trout over 20" and in almost all cases your first 5 (or whatever the daily limit is) must be counted as your daily limit no matter if you keep them or not !!!
Hope that helps if even a little !!!
