Good call on Wesport. Great fishery but when you have a ten year old with you dont take chances. The problem with charter boats and ten year olds is the charter boats dont go in whenever you want to. Your looking at long days, unless you and your family are the only ones on the boat.
Theres a couple of guys that guide out of sekiu, smaller operations. I cant receommend one as I have no experience with them, just see them running around.
The other option is to rent a skiff. That way to can come and go as you please. In early July it can be slow in Sekiu as alot of kings are still staked up in the ocean, but there are fish to be caught. Most guys spend the first couple of hours of daylight fishing then call it a day.
Call Van Ripers and ask about boat rentals.
http://www.vanripersresort.com/fishing.htm