Fabric and Fibre Postcards: Day 47

At last....on to the last couple of days of Postcard blogging!
It's been an interesting time for me,if for no other reason that I have had to make a daily posting on the same theme.

Now,can you come up with helpful suggestions please ?

After participating in the recent ATC Haiku themed swap over on Aus_NZ_Artquilters, I'm wondering if something similar could be successfully done with Postcards!

I can visualise the backing, as per the 'normal' fabric postcard,being anchored only on three sides(the two 6 " and one 4")
but how could an insert be contained,unless the card was mailed in a clear cellophane envelope?

Also,if there is an insert (even if it's only a small sheet of paper) will the postal authorities deem it to be a letter rather than a card?

I'm looking forward to asking the local (patient and helpful) Post Office staff and seeing their reaction.
I guess I better make a card first,so they can see what I mean.