RE: the peppers, depends on what taste you want. Use roasted peppers -- homemade or packed in Olive Oil for a more savory taste or hot peppers with other spices for a tex mex type taste. Otherwise use fresh chopped bell peppers -- tri color would look & taste good.
RE: sweet -- Splenda is a 0 calorie sweetener but fruit has fructose = sugar, but if you can have fruit try Sugar Free (like Smuckers) fruit spreads mixed in or unsweetened applesauce with cinnamon or chopped pineapple (if you can have this on CKD)
Obiwan really knows his stuff when it comes to food!!