Wow, that worked perfectly. DT Register has a lot more flexibility then seen at first glance. I hope to be able to use it for some larger projects coming up.
Is there a way to put blank lines between custom field groups? I just think it would look better.
To put in blank space between custom fields, you'd need to use a TEXTUAL custom field. The "Text" for the field supports HTML so just put in <br /> once or twice, save it, order it in between the appropriate fields... then enable that new field for your event.