My thought was if the family and caregivers can use them also then its possible a lot of these cards are not mailed and they are shared among these people. ( so hand delivered)
so, glitter sequins lumps bumps flowers you name it, its fair game. its not like sending them to active duty deployed troops.
so, to me that meant you could make all the things you wished you could send to the troops.
but, to answer the question no i do not include notes stating that lumpy cards or square cards or lumpy&square cards will require extra postage. ( I very rarely make A-2 cards and most my Christmas cards cost me about $2.00 per card to mail so, I take that as the norm and make what I want anyways. )