There was a post on the DoK FB group that had an idea. It was essentially adding a checkbox that says "if you check this box, you can not register" and leave it unchecked by default. Some of the spam-bots will automatically check uniquely named check boxes, so it will check it, then instantly fail registration without troubling you with a junk account.
I have no access to any code whatsoever for DoK, only the admin control panel thing, but since you have full code access for here, figured I'd mention it.