Mast Rake

I certainly don't have any answers for you, but I did do a few minutes of searching and found there's a somewhat active Sonata sailing community. They have a number of brochures and technical articles on the site, on topics ranging from anchors to yacht lift, including at least 4 articles about masts and steps.

imo, the mast on this boat appears to be light and bendy, and will be difficult to tension into a rake, but there is a slight drift to the shrouds so some rake should be developed using both backstay and shrouds.

To tension the forestay you might try using the vang. I'd suggest a running backstay, but with this mast I suspect it will do more to distort the main than aid in tensioning the the jib's luff. Remember that by raking the mast with the back stay and compression you are also reducing the forestay tension a bit, and flattening the upper portion of the main.

Other things to try to improve weather helm include adjusting the daggerboard depth, and sailing with a bit more heel. You have a racy hull, and since weather helm very literally causes drag to slow you down, you're likely to have some difficulties convincing the boat to do what it's been designed not to do.