Bathroom exhaust fan location ?

Hi All, Recently bought a house which does not have an exhaust fan in the bathroom. It does have a skylight which we open during showers to allow for ventilation. This works fine in the fall/spring/summer months, but you can feel the cool air coming in in the winter. I would like to put in an exhaust fan, but not sure about where it should be positioned. I'll explain the situation and photo is attached. Can't see the skylight in the photo, but can see the walls leading up to it. The shower is enclosed with glass walls on two sides with a fully open top. About 1/2-2/3 of the area above the shower includes a ceiling above it with a light fixture. The ceiling then has four walls which are angled and extend up to the roof area where we have the skylight. Sorry, don't have a better picture at this time, but you can see the angled walls. When showering, the steam obviously gets on the ceiling above the shower and also goes up to the skylight portion. One option I see is to replace the light above the shower with an exhaust fan. However, since this isn't the highest point of the ceiling, I'm afraid that the exhaust fan won't be powerful enough to catch all of the moisture and we will continue to have the problem of moisture build up at the skylight area, leading to potential damage to the drywall. Not sure if there are any exhaust fans that can be installed with the skylight in place. Ideally I would like to leave the skylight as is to use in the warmer months. Thank you in advance for the help! Attachment 44788 (http://www.doityourself.com/forum/attachments/ducting-air-circulation-ventilation-systems/44788-bathroom-exhaust-fan-location-bathroom.jpg)