Both high/low rigs and Carolina-type rigs will work. And, most baits will work, both live bait and dead bait. Although uncommon, I watched Redfish catch two guitarfish one day on an artificial lure so if they’re hungry the sky’s the limit.
I would use a fishfinder rig with a pyramid weight on a slider and an at least 60# wire leader with a 3/0-5/0 circle hook. For bait I would use a live/fresh dead medium-large sardine or small mackerel. Smelt is a good bait while still alive, and squid is o.k. when there's not much in the bait department. I would fish from where the breakers end to the midsection of the pier. I have hooked the majority of my shovelnose in the morning to noon, though I am sure they would eat at night. Just be prepared for leopard shark and bat ray bycatch.
Most are caught during the day although the largest one I ever saw was caught at night. And, most indeed seem to be caught from just past the breakers to the mid pier area. are caught in the mid-pier area. Having said that, guitarfish haven't read this thread and may show up from the shallows to the deep-water end of the pier. And, to some extent, every pier is different.