I don't see why a shower would put out more moisture than using the shower in a bath/shower setup. You can minimize the chance for mold to start by making sure air can circulate into the shower area. Most tub to shower areas will have open space above the shower curtain or door that helps the area dry.

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If your shower area has a drop ceiling the air flow could be limited. Keeping the curtain or door open after a shower will help the area to dry. Using a mold control product will prevent a problem from developing. I use Concrobium Mold Control, but there are other brands. I spray it on once a month and let it dry.

A through-the-wall Vent Fan would allow excess moisture to be vented outside. You would have to connect it to the nearest outlet box with a piece of 12-2 wire.

thanks so much for the info. I didn't know about Concrobium...thank you!