It comes down to breaking the content down into the smallest
logical sets. Think about what will be static across configs and
what will need to be updated. Rather than pushing out one file,
combine the files using either menu builder or an external HTML
template.
I would also ask, does the functionality change or just
look/feel/fields available. If it is just look/feel/fields
available, I would suggest creating training on the defaults and
stressing that while their interface differs, the performance is
the same.