Scarf joints have no effect on stiffness.

I cut the strips for my stripper canoe from cedar fence planks which were only 6 feet long. Lots of scarfing on that boat! The reject plank were used to my fence. The planks were slash cut, so when I rip off a strip the grain was vertical. I use a skilsaw, not a table saw, the mere thought of which terrifies me. The skilsaw has a narrow kerf finish blade for minimum waste, and I added a ply base with a zero-clearance slot for the blade to prevent splinters, with a guide that is x3 the length of the base so the cut starts and ends straight. I cut the strips 1/32" over thickness and run them through a table router to clean up the inside, since the outside is easier and more important to sand smooth.

There were 2 or 3 scarf joints on most of the strips glued with Titebond III, which I've used successfully before. I cut scarfs on a miter saw years ago but changed to a bench-mounted disk sander, with a guide clamped to the table to get the 6:1 angle consistent, and made up a jig (pic) for gluing and clamping the joints accurately; the gap in the jig is so the piece can be removed after clamping. Titebond thickens up enough to minimise sliding about under the clamps in a few minutes so the piece can be removed which gave me time to prepare the parts for the next strip - very efficient use of my time!

I'm not sure about using Titebond instead of epoxy on a SOF: in a stripper each joint gets supported on both sides, in a SOF boat the stringers are on their own. I have found Titebond softens if soaked for a long time, regaining its strength once it dries out. If that happens in a SOF the joint could fail, so make sure the frame is well sealed before skinning.