We hang ours up high on the front of the tent, above where Jeannie has hers.
We made a big U shape out of metal conduit pipe, with metal elbows. It all comes apart and goes together easily so it can fit in the van, there are small screws at the joints.
There is a joint in the middle of the bar where the sign hangs.
The U shape is as wide as the front of the tent., and we use ball ties to lash the sides of the U to the front legs of the tent.
Then the banner is hung on wire loops we made from the pipe, metal shower curtain rings work too. If it's windy, then we switch to using bungee cords on the corner of the banners so the sign won't blow around.
Originally we used PVC pipe, but found it too droopy in the middle of the U, where the sign hung, so switched to metal pipe. Copper would work too, but would be more expensive. I've also seen shops that lash bamboo together to use as a structure to hang signs.