How do you snuff out the flame? Just put the pot on it? Does that tend to crush the tea light?
My minimal experiments with wind screens suggest I need more air flow. Yours seems to have minimal air inlets. Did you test this pattern to optimize?
I might add a circle cut from the bottom of an Aluminum Pie Pan to use as a base to protect the ground and radiate heat.
Is that 1/2 inch hardware cloth pot stand (from a 19 square x 4 square piece)?