Red,
Have you tried the fusible mesh products? The fusible type product is great on onsies to keep the fabric from stretching. It is cut-a-way though. But, it is promoted to be soft against the skin, especially for baby clothes.
This is the product I have used:
Floriani's No Show Fusible Mesh (Beige)
Try going to:
www.Embroidery.com
And search for this product. There is a demo video you may want to watch. I tried to put a link to the video here.
I have also used the Janome no-show fusible mesh, it also works well. Have had no complaints about it irritating the skin.
Vicki

Here is a link that might be useful: Floriani's No Show Mesh Video

Just try some soft weight tricot or nylon. Sew your embroidery, tear or cut as close as you can and then use a form of "wonder under" (or the like) - iron it on the "soft" stuff and then iron it onto the back of your finished embroidery.It costs very little and it's very easy to do. Chris