Hi Martin

As the map is only 2m across it shouldn't be necessary to use the balcony or a mast. A supported bar over the narrowest width would give a central position and stability/security. 2 lighting stands (pro ones) with a pole or timber between will give a support for the camera. Add weights to the base of the stands for security. Tether as previously suggested to position and shoot. If you have a background support system (for paper or cloth rolls) that'd be good option to suspend over the top (they usually span 3m for 9 foot rolls). Use a universal clamp to attach camera (see http://www.theflashcentre.com in Leeds or Calumet). Next issue is the lighting - ideally powerfulish flash, otherwise you could be mixing with ambient. If powerful enough bounce it off the walls and/or ceiling (if all lightish and similar colours -  pref white). If not, aim each at furthest corner from the light, from as far back as possible.

As a dry run, you might want to try your set up with a white bed sheet a few days before - see if the chosen method is feasible and lighting is even

Good luck

Derek

Derek Trillo
http://www.insightimages.co.uk