Having long page names is not very user friendly as well as it is not very good for SEO. I would rather recommend adding another field to the page type. The Document name field will contain some shorter version while the extra field can be filled with the long version. Then, in the transformations you will use the extra field to display the long version of the page name.
There is a way how to change the node alias and node name length. However, this can cause severe performance degradation so it is strongly recommended not to do that!
Please see web.config keys documentation and search for CMSMaxNodeAliasLength and CMSMaxNodeNameLength keys and their description.
Again, these changes are not recommended - the DB index can have max 450 characters. These fields are indexed and if they exceed 450 characters, the performance will be decreased!