I use frozen shad all the time. I usually put twenty in a long sandwich zip lock bag flat in the freezer so I don't have to dry them. They will do well in the freezer if they are not clumped together and there is no water in the bag. I split a block of Ice and put one half of the block in the bottom of a small well insulated cooler, put a few bags of shad on the block then put the other half of the block on top (krystal cube ice works well if you cant get blocks) Only open the cooler when getting shad. Keep it in the shade and it lasts all day.
But once they have been taken out of the freezer if you put them back in the freezer after a trip if you have some leftover they will be very mushy if used again.
If we can net live shad we use a live well made out of the bottom quarter of a 55 gallon plastic drum that is hooked to a cheep live well pump hat I clamp to a small lawn mower batter. The tank has an over flow allow the water to constantly circulate. Works well on land or in a boat. Some shad will die quick but if you keep the pump running some will stay alive as long as your battery lasts!
If you put some additive in the water (stuff usually for putting in live wells for bass) and some ice you get much better results.
Hope this helps a little. I have caught nearly all species on these frozen shad (Large Mouth, Stripers, White bass, Channels, Green Eared Sunfish, and even some carp lol)