I've used this stuff a lot in my wargaming hobby to make scenic water features like rivers and ponds. The fumes aren't strong at all so I wouldnt worry about that. Regardless of where you allow it to dry, make sure it's covered the whole time or any spec of dust or fly that lands on it will be part of it forever.
Two words of advice:
-Mix it REALLY WELL. Make sure it is thoroughly mixed before pouring or you might end upwith stucky, uncured patches.
-After pouring it, breathe on the surface gently. This makes the air bubbles disappear. Do this several times until all the bubbles are gone.
Good luck. It's a great product.