Snow: ya got mail
Boldy:
Maybe this is a stupid remark, cause I don't know how you coded the submitter, but to me it seems you allready have the foundation for such an option ready to go.
You allready offer bannerless submissions for a monthly fee.
So IMHO all you have to do is take that option add a check to it when people upload the galleries in the submitter to crosscheck the ref codes used on it with what you have on file (a small sql database would do it)
Saves ya a lot of time policing it and only makes the upload a few seconds slower. BUT saves saves you a whole lot of reprogramming ;)
My
CC