Vintage Projects has quite a selection of plans, designs and instruction booklets that were published "back in the day". Some are quite detailed, and are provided as PDF files and the like. Subjects range from power and sail boats to farm and construction plans, kids toys, and power tools. I’ve previously linked to their Sandblaster plans. This page links to their Power Boats plans. There are several skiffs and small craft, including what they call "Large Skiff" which is really the Atkin’s Happy Clam design.
Of note is the 25’ Cabin Cruiser. Some of the pictures are worth a laugh, to me, but the details and "how to build" are pretty well spelled out. I think this was originally in a Popular Mechanics publication. If you are looking to build in a "classic" style, there may be some diagrams and pictures that help explain the "how-to" aspects, even if you don’t use that design.
The Outboard Motor Cart also looks like a design that could be adapted and used to this day.