Oh the fun!
Mark, I think a small clarification on my understanding of the use of Jointer Plane might be useful.
As a devotee of the COS (Cult of Schwarz), his video Course, Medium and Fine helped me "see the light".
A Scrub plane is more for house carpentry, for reducing the width of 2x stock. The sole is a bit short and the blade way too narrow to do meaningful work on faces of boards. I used one to thickeness stock, it took for freak'n ever. I tend to by into the carpentry application over woodworking.
A #5, #6, Fore, or Jack plane is the equiv of a powered thickness planer. It removes a lot of stock quickly. The jack can have as wide a curviture on the blade as you'd like. No point in flattening the sole (unless its really really out).
To our original thread question, I'd not worry too much about buying a Jack. You can get them for cheap. I find them at auctions or online for under $10. I have a few lying around if you'd like to PM me.
The Jointer Plane is equiv to a wide belt sander. It takes the roughly flattened board from the Powered Thickness Planer or Jack plane and makes it uniformly flat.
It took me a long time to understand uniformly flat is not smooth. Thats the next step for a #4 or #4 1/2 smoother, hand sanding or random orbit sanding and maybe a cabinet scraper.
As an aside, the Jointer Plane has other uses beyond stock prep. It can flatten parts, like mullions or rails and styles for doors or picture frames etc. It can be used to tweak the fit of doors.
I also endorse Bill Anderson classes. I took his first class a few years back. He is a wealth of knowledge and a fine teacher.
Go, I think your solution is just fine. I've seen long sleds with the stock shimmed to make a badly warped board stable and "flat" enough to run thru the thickness planer to make one face flat. Then flip the board over and run the other face thru. Depending, you could be looking at a lot of passes thru the thicknes planer. Your approach using the jack plane and winding sticks is great!
Dang, I sure do type a lot.........
Jim