End-user fillout form dropdown instead of checkbox for Group(s)
I found a solution. Not sure if it's the best way, but it works. I use a script and put the checkboxes inside a table with the  using the class called in the script:

&lt;td class="example"&gt;
&lt;input type="hidden" name="group[11]" value="" /&gt;
&lt;input class="example"  skiplabel="1" id="group_11" name="group[11]" type="checkbox" value="1" /&gt;
Utility Advocate
&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;

&lt;script&gt;
jQuery(":checkbox").on('click',function(){if(jQuery(this).is(':checked')){jQuery('td.example :checkbox').prop("checked",false);jQuery(this).prop("checked",true);}});
&lt;/script&gt;


If anyone has a more elegant solution, please, I would love it hear it. : )