you can purchase a fusable interfacing- press that to the back (it is what is used in collars/cuffs of nice shirts=ect. it stays in - there are different weights-choose a lightweight one- it has fusable on one side- the other side is a lightweight fabric-a little like a dryer sheet-but different-
it stays soft- and would protect your seams without really adding weight or bulk. visit joannes-or a store like that and ask for a fusable (stay in) interfacing- they will know what you need