Most of the times default Settings .ie Indoor / Outdoor profile will do. Meraki Dashboard offers us such profiles with standard configuration.
If you face coverage or connectivity challenges in your environment you may consider conducting RF Site Survey. You may tweak settings from the Dashboard as per the recommendation of the Survey Report.
MR53E is a good piece of Hardware supporting external Antennas and WIDS. I believe this box can handle extreme conditions.
Is there any specific issue you are facing in your environment?