Oh wow! That is a beautiful ballon! I hope they see the ping! Thanks!
As far as signs go, I have found that if I mount my bumper stickers on magnetized sheets, that can be purchased very reasonably from either hobby shops or photo shops, the bumper stickers can be removed easily to go through car washes, etc, or just when you want to change the bumper stickers. Seems to me that this method would work for signs as well.
The three chapters in Texas: HAT chapter in Houston, HOT chapter in the Austin-San Antone area, and the North TX chapter are talking about organizing a joint chapter event at the Geo Bush Library at Texas A&M. We are just beginning to test the waters for this meeting, and don't have any of the details worked out, yet, but will keep you informed. Otherwise, if you want to drive to Austin, we will arrange to have a meeting for you and your group.
Good luck on implementing your excellent idea!