M.L.
I was only at a shore once and i don't remember it being exactly like a baseball game where you could walk through peanut shells on the ground, but i think you are rright to ask and be cautious. i think the actual beach water part might be ok but any board walk really could have dropped food and contamination..
Maybe an allergy support website group might be a better place to ask, I would have hoped someone here could tell you but i think you would get people more focused an aware on an allergy site.
what about disney?, there is peanut products there too I think, maybe easier to avoid but still there. man, my heart goes out to you. what a tough issue to have. not many people understand it.