What you use sort of depends on the results you want. I have lined or doubled fabric before, I have a partial bolt of a very thin bleached muslin I use, I have also used poly blend batiste. Sometimes if I want to use a particular fabric for something but it is a "craft" and not a "quilting" level piece of fabric, I will line it just so when/if the original fabric wears away, the muslin will be there to at least hold everything together.
Keep in mind that just like for many of us when wearing white pants, neutral off/white is often better for disappearing than bright white. But maybe bright white gives you the effect you want.
I have a project where I have a set of 1970s cross stitched blocks on a terrible fabric
For that I'm going to prequilt the blocks down to sized scraps of warm and natural and do close up work around the cross stitch, then put it all together with wide sashing (with no W&N) and then a full layer of thin batting, the quilting design will run in and out of the border and tie into the blocks. Have debated about just lining but there are about 80 zillion issues, one of which even though the design were prestamped, the blocks are warped and not consistently sized.