A curtain may only move the overspray problem to another place. A cubicle is better but you need to get rid of the OVERSPRAY or the overspray will linger in that space and YOU and your client risk inhaling it ... as you may know tanning solution can stain the lining of your throat/lungs and cause breathing problems in some cases. Also the room can get very dirty with overspray. A good extractor fan is always the best solution and choose one which has a WASHABLE filter (saves money and is a much better option - plus you can rinse them clean and the filters don't smell of 'old' tan). Here's a video which shows how airborne particles linger until you extract them using a machine. If you invest in an extractor make sure the equipment has an LEV report which proves the equipment has a good airflow which complies with UK Health & Safety (SR13) ... if you need more advise please ask!