Welcome to the VMware Communities forums.
You can use these steps to change the snapshot location for a VM - kb.vmware.com/kb/2007563.
An alternative to deploying a datastore that is pretty much filled by a single VM is to use a raw device mapping (RDM). With an RDM the VM is allocated the entire LUN rather than using a VMDK and datastore. That avoid the situation where you have datastores that are pretty much filled right up.
You can create an RDM in virtual or physical mode. Probably in your case a virtual RDM would be the best as that provides snapshot support. A physical RDM has more direct access to the LUN, but snapshots are not supported. A physical RDM can be up to 64 TB in size, while a virtual RDM is limited to 2 TB.