Baby Suriname/Guyana boas should be fed mice...your preferences will not do your boa any good.
There are theories as to why some Suriname boas have trouble digesting rats early in their life and I'm not trying to downplay anyone's theory but regardless of theory the results are known...Many decades ago pioneers (so to speak) killed baby Suriname/Guyana boa feeding them rats and learned that digestive problems can be avoided by feeding appropriately sized mice for the first year.