Mike Buckley has written an excellent article:
Coping in the Wilderness - Low Impact Kayak Camping
That can be found on the Sea Site, in the article he describes various ways to reduce the sea kayakers impact on the environment. Many of his ideas/methods end up with something burning on the obligatory camp fire. I don't want you to get me wrong I love feeding the arsonist in me with a good fire as much as the next person but assuming you don't need a fire to cook with why bother having one at all?
After all a (non sand) site prepared and cleared by the most avid "Scout" among us will still leave evidence, at least for a few weeks and in many cases a lot lot longer.