From Oracle Support:
Output to CSV Width Limitation of 45 Inches
In Report Design Aid, the maximum width allowable in Print Setup when setting a Custom paper size is up to approximately 45 inches. There is no way to override the maximum width in Print Setup. Therefore, the limit on the number of columns in RDA also cannot be overridden. When formatting a report for CSV output, all the information required for the report must be inserted in the available design space.
If this is not possible, as a workaround option, in RDA rather than using the option for Export to CSV, use the Database Output functionality to output a Comma Delimited file with a CSV file extension following the steps below:
1.Focus on the appropriate section and click on Section|Database Output
2.In the Mapping Targets screen,
◦Double-click on the Type cell and select Comma delimited file
◦Enter the name of the file with or without the path location.
◦Click Next
3.On the Mappings screen, select the mapping for each field to output to the flat file
◦For each Target Column, Double-click on the Source Section and choose the same section as in step 1
◦Double-click on the Source Object and choose the appropriate RV or BC object.