Hi kbosworth,
Thank you for your purchase.

Unfortunately that request is out of the box of our plugin and it will require some code customization.

I can give you some guide where to look so maybe you can find the solution.
In file ../wpdatatables/assets/js/wpdatatables/wpdatatables.js around line 606 you will find this code

 * Apply pickadate
 */
var dateFormat = tableDescription.datepickFormat.replace(/y/g, 'yy').replace(/Y/g, 'yyyy').replace(/M/g, 'mmm');
var datePickerInit = function (selector, additional_params, state) {
    if( $('#wdtDatePickContainer').length == 0 ){
        $('<div id="wdtDatePickContainer" class="wpDataTables"></div>').appendTo('body');
    }
    var input = $(selector).pickadate({
        format: dateFormat,
        formatSubmit: dateFormat,
        selectYears: 5,
        selectMonths: true,
        container: '#wdtDatePickContainer',
        onClose: additional_params,
        firstDay: 1
    });
    var picker = input.pickadate('picker');
    if (state == 'opened') {
        picker.open();
    }
}

the "selectYears : 5" gives the select box 5 years in past and 5 years in the future. 
So I hope this can help.
If you can not find the solution we can offer you our paid customization service.