Hi,
if it's the same domain (or trusted one), then a single SVM can do the work, I have merged a few file servers to a single SVM before, and I don't see any issue with it.
As a best practice, I try to use hidden ($) shares where possible, and match each share with its own identical CNAME (to make DR tests and migrations easier). And sometimes uses DNFSn (although I don't like it - it does the job).
There's no problem pointing as many CNAMEs as you like to a single interface (make sure to set SPN's). and to use the RoundRobing or the NetApp DNS load balance feature https://www.netapp.com/us/media/tr-4523.pdf to spread the workload on a few nodes. you may want to consider splitting the access to multiple LIFs/SVMs to accommodate scenarios as:
Need to expose a share/export to a DMZ or a 3rd party.
A heavy workload that you want to bind to a single node where the volume resides (to overloading the cluster network).
Prepare for known splits (geographically, or different entities/departments that might get sold off)