All I did was make my banned users group the only group viewable in showgroups and then deleted this part from the showgroups template:
<if condition="$moderatorbits">
<!-- moderators -->
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<td class="tcat" colspan="4">$vbphrase[moderators]</td>
</tr>
<tr>
<td class="thead"> </td>
<td class="thead" width="50%">$vbphrase[username]<if condition="$show['locationfield']"> / $vbphrase[location_perm]</if></td>
<td class="thead" width="50%">$vbphrase[forums]</td>
<td class="thead">$vbphrase[contact]</td>
</tr>
$moderatorbits
</table>
<br />
<!-- end moderators -->
</if>
Deleted this from showgroups_usergroup:
<td class="thead"> </td>
<td class="thead" width="100%">$vbphrase[user_name]<if condition="$show['locationfield']"> / $vbphrase[location_perm]</if></td>
<td class="thead">$vbphrase[contact]</td>
Then deleted these from showgroups_usergroupbit:
<td class="$bgclass">$user[onlinestatus]</td>
<if condition="$show['location']"><div class="smallfont" title="$vbphrase[location_perm]">$user[location]</div></if>
<td class="$bgclass" nowrap="nowrap">
<if condition="$show['pmlink']"><a href="private.php?$session[sessionurl]do=newpm&u=$user[userid]"><img src="$stylevar[imgdir_button]/sendpm.gif" alt="<phrase 1="$user[username]">$vbphrase[send_private_message_to_x]</phrase>" border="0" /></a></if>
<if condition="$show['emaillink']"><a href="sendmessage.php?$session[sessionurl]do=mailmember&u=$user[userid]"><img src="$stylevar[imgdir_button]/email.gif" alt="<phrase 1="$user[username]">$vbphrase[send_message_via_email_to_x]</phrase>" border="0" /></a></if>
</td>
And then put a link to showgroups.php in the navbar.
The reason and how long, I don't know, I haven't got that far yet. But what I did is a start.