I have a group of friends that do a pig roast once a year. Different location each year, never released until a few days prior to the departure. And then it's an actual race to get to the GPS coords, once released to the group. They actually bring a pig along with them. After the 'grease the pig / catch the greased pig' debauchery wind down, they tie up the floatilla near shore, and take both the pig and fire off the boats. Dig a pit in the sand, bonfire, roast, eat, drink, through the night. etc.
We know that fire and boats don't mix well. Our compromise is a small propane like grill that we set up on the swim platform when in use. Once cooled and cleaned, it tucks away in the Laz.
Anything with open flames / hot coals on a boat puts me on edge. I can't imagine having a hibachi or otherwise open fire type grill hanging on a rail or sitting on a deck as much of the cruising world does.