You could, but unfortunately, no, it is not recommended.
Here is an explanation from Change Individual Master Data Fields - Internal Orders - SAP Library
1. Define your own data element in the Data Dictionary. It requires the same data type and field length as the matching data element provided by SAP.
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CAUTION
The data type and field length MUST be the same as those for the data element provided by SAP. If they are not, data conversion is not triggered when you update to a new release.