I'll do scaled, headless, gutted Lakers in foil using squeeze butter on the foil. Stick some half cooked rice and celery in the cavity. Maybe toss in some lemon slices... mainly on group trips.

Sometimes I'll cut up Walleye fillets into bite size pieces with a white sauce w/dill or whatever is available...

Either way, I bake on the grill using two layers of foil. When it puffs a lot, it's done. Lakers can take a half an hour at least.

Burn off the stinky stuff off the foil and pack out what doesn't oxidize.

I use to do a vegi pack using foil as well. Taters, carrots, celery, maybe onions... butter and seasoning. I do that at home on the grill too. Never had any luck at all sticking anything in the coals. Maybe I didn't do it right.

BTW - Last trip, I breaded and fried using the dregs from a Nacho Cheese Doritos bag for breading. Not bad! I use minimal oil for frying preferring to add some squeeze butter at the end.

Butter doesn't really need to be kept very cold. Cool seems fine IMO.