IIRC, solar stills in a desert environment/survival scenario are credited to be a waste of time/energy, because they give so little water vs what you spend building them.
Now I would expect such a still to be effective near a pool of water ! You have all the water you want without exhausting yourself.... the only job of the still is to separate salt from water.
+ in this "Bug In" scenario, you can prepare/experiment/test your still well in advance...
it could be more of a solar distillery than a solar still <img src="/images/graemlins/grin.gif" alt="" />

So, in these conditions, a solar still might be a good thing to consider...