Is there a low light plant, that will grow under a pepper tree, and between two oleanders, that grows about 3-5 feet tall, in southern California?
I highly recommend Taxus baccata 'repandens', English Spreading Yew. One of the few conifers that grows in shade! Does well in sun but in S. California I think you'd want this in the part-shade to shade and you want this to grow under your pepper tree. Don't prune this...it gets up to 3' with graceful, arching branches providing an excellent 'foundation' plant...or skeleton plant. These are plants that 'pull' your landscape together forming the 'bones' of your landscape.
Let me know if this isn't a good plant for your area. I've little experience with plants down there..