I've been on couple of trips out of Westport pursuing albacore with a fly rod. It is an adventure to say the least. Big strong fish that humbles 12 wts and causes one's back to get sore.
The last two times out was late September -- Great fishing and great conditions. Flat seas and warm (very unusal).
A bunch of guys and I booked an entire charter. The Captain was game, but very much unaware of fly gear and its capabilities. It is possible to work with a charter to arange what you want. Just remember the culture of harvasting tuna by the ton and more is always better.
Its great to read about fly charters and for that matter publications featuring tuna off the Washington/Orgon Coast and the fly rodding sport they provide. Tuna on the fly is a very enjoyable blue water fly fishing expereince.
My last experience will always stay with me -- Calm blue sea, tuna streaking under the boat as I worked the fly back ten feet under the water as it vannished in the mouth of an albacor.
Salty Dog -- Good luck and post the experience. The more who play in this game the easier it will be for all of us.