There’s a setting in ACFs to associated the field group to a CPT. This will result in having only those fields display when a new CPT is created.
I completely agree, it really should be part of the platform, if only as a checkbox. In general, it’s probably easier to deal with the few customers who might abuse this feature, rather than having to reimburse all those who are legitimately tax exempt. I think I’ll probably end up coding it that way.