add some rocks underneath while I have the stove running
A friend mentioned this as well... In fact, he once placed a stove we built on a bed of rocks. Returned and asked if I could replace the bottom as the heat sitting on the rocked gave the bottom a hell of a series of funky shapes! Haha!
Placing rocks help retain heat, I understand that, we were kayaking and only area to sleep was on a sand bar... We placed from our fire, hot rocks and set them in holes, covered with the sand and placed brush over the sand with our small tarp over... worked heck of a lot better than right on the sand and let the earth suck the heat out of our sleeping bags.
Curious though, a standing stove with rocks below (not touching the bottom of the stove) how much additional heat do you gain? It's doesn't take jack squat for time to make a reflective/heat retaining base of rocks. Good idea.