Wonderful quilt! Love the pattern. I'm gonna say it again...I am self-taught. All I knew about was SID. I would cut fabric into 8 inch squares and resew them just to have a ditch to stitch in! I'm snuggling with one now! It's over 10 years old, no clumped up batting etc.
Then, I discovered this board and have learned volumes over the last year and a half. Love the painter's tape for a guide!
Bottom line...your quilt will be safe following the guidelines for the batting.
I am a fan of the serpentine stitch. I'm using it today to finish quilting the current project. It allows you to be imperfect at straight stitching. Plus, it looks like the ocean on my jellyfish fabric!