Different laws in different states - someone local will be along shortly to offer state specific advice.
Generally though: Under no circumstances unload in a restaurant or anywhere public like that. Storage in a backpack is normally considered concealed.
I might simply tuck the entire rig in my waist band al la Mexican carry but with a holster.
BTW - that is precisely why I prefer OWB hostlers, that and I do not need over sized pants to comfortably accommodate IWB styles.