As you can see from a side view, the wire portion does have a gently curved bend backwards. The solidago stands straighter out, filling in from the sides nicely.
I also place shorter laterals of the solidego on the underside, covering up the foam from the back view.
You can see some holes in the side of the foam cage where you can insert more solidego.
Finished with the solidago making a pleasing green collar that contrasts nicely with the wire collar as it covers up your bouquet holder mechanics.
You can finish the backside with gluing on fresh leaves and then using the discarded stems and floral clay to create a beautiful hand tied look. I do cover this technique in tight hand tied bouquets.
The final look is quite convincing and no one will ever know that the bouquet is actually created on a bouquet holder.
You may prefer winding decorative wire around the handle itself. This can be completed before you start to green or flower the holder because the holder can be soaked in water with no damage to the handle treatment.