and if you can still get an Island Outfitters boat, ask if you can get Elliott (assuming he still does charters)...we rented a bunch of their boats two years ago and he was the best of the group (lol...sorry if any of the other guides are here, but that's an honest assessment for at the time).
And no, my name isn't elliott
Keep in mind as well, if you want your best shot at the salmon, the morning charter would be the way to go - may be a pain getting the young ones up and rolling, but being so far away, you gotta do it right! Don't let a guide take you locally to the waterfront or something - go to Sooke, at least as far west as Beechey Bay.
If you can't get a big boat on short notice, you should really consider 2 boats - you could maybe have 1 girl in each and have a 'fish off'....the boat with the biggest fish wins a prize?? huh huh They can easily troll next to or close to each other.
Only other consideration I can think of for those kind of numbers would be Candian Princess in Ucluelet - but thats a long haul from Victoria.
Best of luck