I would suggest using a thinner muslin for your foundation fabric. It will keep the quilt top a little lighter and it is reasonably priced too.
You might consider not using a base fabric. There really isn't a need for it, if you are going to fuse down your leading pieces.
It would be cheaper to purchase a couple of applique sheets to work on, when fusing down the leading. These are reusable too :wink: :D:D:D