I have not checked closely but Geo::Point seems to be for geographic coordinates, so latitude and longitude and not projected coordinates such as UTM. (Edit: actually it does but it uses proj4 which is long deprecated). It also seems not to handle Z and M coordinates, and neither does the parent Geo::Shape class.

For a single part polygon or polyline one just needs an array of coordinates (vertices), so an array of arrays would do. Maybe each vertex could be blessed into an array based object if that makes other things easier.

Multipart features are collections of polygons, polylines and points (one type per feature) so would be a different object class.

Then there are geometry collections which can be a mix of feature types. e.g. http://postgis.net/workshops/postgis-intro/geometries.html