I would like to do this instead of passing in answers on the URL. This currently doesn't work because in the add_response() function in application/helpers/remotecontrol/remotecontrol_handle.php (around line 2186) it checks if 'submitdate' is not set, and if it's not it gets set to the current time assuming the response is completed.

In order to do this it seems like there are a couple options:
1) Don't assume the response has been submitted if it isn't specified
2) Still set submitdate to current time if it isn't specified, but if 'submitdate' is passed as null or empty it should be removed from $aResponseData

Currently if you pass in null or '' for the value, the submitdate gets set to all zeros. I think this code could work instead, which would be option #2:

if (array_key_exists('submitdate', $aResponseData) && empty($aResponseData['submitdate']))
unset($aResponseData['submitdate'];
else if (!isset($aResponseData['submitdate']))
$aResponseData['submitdate'] = date("Y-m-d H:i:s");

I have tested this code and it seems to work fine. Same could be done for datestamp and startdate, although those don't matter as much to me. Does this sound reasonable?