Trim and change to null before saving

I have users that like to accidentally add extra spaces to the end of test fields and sometimes even the beginning of text fields.

I know I can specify the field name and do a trim in the before aded and before update events, but is there a safe way to loop thru all fields on the page and do it easily?

Also I know I can go into each text field in the page and click on "Insert NULL values instead of empty strings" but sometimes I forget. Can I change all the fields to null if empty while I'm looping thru the fields above?

Thanks
Alan