From what I can gather, there isn't a real way outside of creating a map for everything. With Rune, I find most of the 1/2 byte looking characters have Plane set to 0 and BMP is set to True, but that isn't in all cases.

You will notice that \u23f0 has an extra space and \ud83c\udd8f is missing the space. I guess I'll just map out the ones I'll support and leave it to the user to append a space when they need it.

Examples I used, where it states Padded: True, means I added \ufe0f: