Ash10500, There's no need to make an object a sprite to add Bullet Behavior. A tiled background is probably a better match for Yttermayn's needs.
By default, Tiled backgrounds are not animateable.
The three solutions I'm aware of are yours- moving the background with a looping mechanism*
Having one tiled background per frame- not recommended for long animations
Having an animated sprite overtop, if only one piece of the background needs animation.
*see for a background approach very similar to yours. The anti-choppiness solution will probably come in handy for you.