Is it possible to define a 'richtext' fieldtype as 'MEDIUMTEXT' in DB? Some articles are very long and getting cut off when saved to the database. 

Is it possible to define a 'richtext' fieldtype as 'MEDIUMTEXT', or would I have to write a plugin to replicate the 'richtext' fieldtype with a different field attribute defined in defineContentAttribute? Any other considerations to take into account? Such as search, indexing, redactor or otherwise?

Part 2 of this question would be: what is the simplest way to duplicate the RichTextField in a plugin? Can I just extend 'RichTextFieldType' and redefine getName and defineContentAttribute? I tried the following with no luck. 

Update: This creates a 'Rich Text (Medium)' field with the correct DB column type of 'MEDIUMTEXT', but causes the 'Edit Entry' screen in the CP to be blank below the entry title (silent fail?); and if switching to entry type with this field getting a garnish error 'Double-instantiating a transparent text input on an element'.

class LongTextFields_MediumRichTextFieldType extends RichTextFieldType
{
    public function getName()
    {
        return Craft::t('Rich Text (Medium)');
    }
    public function defineContentAttribute()
    {
        return array(AttributeType::String, 'column' =&gt; ColumnType::MediumText);
    }
}


Another option might be to just redefine the columntype manually in the database. Is there any chance this value will ever get overwritten? (i.e. upgrades, migrations, etc).
Defining your a plugin with it's own field type that extends RichTextFieldType might work (haven't tested), but your current code is slightly off.

The field type class/file name needs to be PluginHandle_FieldTypeNameFieldType before Craft will even recognize it.

Also, the ColumnType enum uses MediumText, not Mediumtext.

Really, what we should probably do is make this a setting on the field type because it does pop up every so often and there currently isn't a clean answer.