If I were to be a set designer for the play Gotcha, I would set it in a thrust with the audience nearly all the way around but you do have one wall. I feel this is one of the better options because it gets the feel of the storeroom and also the actors have somewhere to come on without being seen. It can help to put larger objects on the back of the wall too. If you look at the diagram I have made none of the audience are being blocked out and it still have the realistic feel with all the corners blocked. If you were to do this play in the round it would work but you might only see one characters face throughout the play, you might really love them the come back see it from a different angle and change your mind. Its a good way of doing the play and works well as we have been working on it in class, but if i were to do it in front of an audience I would like to play it save. 

This can also help with the lighting if you were in the round chance are you might be lighting up the audiences feet for most of the play and that can become distracting. As its going through the course of the day with a football match going on outside I would start the day bright as though the sun was shinning through the window and as the mid day becomes move dim the light. It also works as the emotion changes in the stockroom and makes you believe the sun is moving in and out of the clouds. A stockroom might be a little run down anyway and not looked after so well so it might even be dull with the lighting also.