The closest that I have come to it is, flannel on the back.

the way i use flannel in baby quilts is either on the top pieced and cotton on back or vise a versa cotton on front flannel on back

I don't. I would try a sample first. The reason I haven't done so yet is because I can't find a flannel & a cotton that are roughly equal. One ends up pulling too much on the other & I end up with a wonky block. Also, you generally want to use a wider seam with flannel than cotton. With my flannel backed baby quilts I do a 1/2" seam on the back to make it more secure. You may want to use at least a 3/8" seam for piecing with the flannel.

Also, flannel really shrinks a lot in the dryer. Be sure to pre-wash everything using the settings the recipient will use (hopefully that's cold water & low heat, but realistically it may not be). I pre-washed some flannel/cotton changing pads on cold/low and they finished at 18"x22". A year later with infrequent use (at grandma's house) and washing on warm water/medium heat, they now measure 12.5" x 17". Granted, I used clearance flannel from JAF because it was mainly to practice my quilting skills, but you want to take that into consideration.

Good luck! It sounds really adorable & I hope you can make it work. If not, I would piece it into the back.

I always prewash all my fabric. Have used flannel backing for baby quilts with no problems. At least the recipients haven't said anything.