Hide the filemaker toolbar and put your own submit button on the layout. Have this button include code such as the following to produce an empty found set, thus hiding all submitted records from the user:
Enter Find Mode
Set Field [YourTable::SerialIDField ; -1]
Set Error capture [on]
Perform Find 
The key, is to specify search criteria in line 2 that will not match to any record in your table.
Thank you I will give that a go.
But how do I hide the flemaker toolbar on customers browsers?