Like the height but not the look of the extension rods? Camouflage it with floratape.
I'm actually planning on bringing up some taller green laterals to help conceal the extension rods, but I'm going to wrap the rods in the green floral tape first.
Obviously if you want to do this step, you need to do it before inserting the rods into the florist foam. Floral tape becomes sticky when stretched, so just quickly wrap it down the rod, pulling at a downward angle as you go.
Don't bother with the very bottom - those parts will be inserted deep into the foam and covered with flowers and greenery anyway.
Now that the rods are camouflaged, they will blend easily into the design when I add the various types of greens.