I don't know about the customizer, not between my hands,
you have to ask to the Makerbot staff.
The good way for you, is ,
first using the other link to have an up-to-date release
of the Ultimate Box Maker.
and second, using the script within OpenScad program,
You will see it's easy and user-friendly way to have what you need,
more over if you use the version including the panel maker, you will be able
to make your own texts and holes panel.
Have fun and keep us informed.