If you own any of my cookbooks, there is a chart for subbing out sugar (whether you want to use maple, agave, stevia, etc). If you want to eliminate all sweeteners (even things like maple) you could try using date sugar (dehydrated and ground dates) or beet sugar, or stevia. I wouldn't use bananas as a sugar substitute. Bananas can alter chemistry of baked goods since they act as a binder.