When I embroider baby onesies and t shirts of all sizes, I cover the back with a fusible tricot fabric. It is very soft and keeps the threads from being scratchy on sensitive skin. I use a beige color so it doesn’t show through on white shirts.
You could use a fusible stabilizer like Sulky Tender Touch cut slightly larger with a pinking shears on the back, or a sheer poly mesh fusible like Sulky Soft 'n Sheer Extra, too.
Oh my gosh I feel like an idiot! I have always left an inch of stabilizer ... I sure hope it was because it was common practice back when I started and that I didn't just do it for no good reason!
Great ideas, thank you. But could you please talk slower. I am so busy trying to read your comments that I am not seeing all the examples you are showing us. Not complaining, just helpful remarks.