Just to be clear, is your sole reason for wanting to do this because of the high datastore activity that concurrent clones generate?
Yes, that is the main reason. It also makes the monitoring logs easier to follow for me without having to filter for individual machine names.
By default vCenter supports 8 concurrent operations. vRA by default supports 2 concurrent provisioning. If you want to change the default provisioning from 2 to someother value after taking into consideration the endpoint[vcenter in this case] can handle it then you can change it accordingly. More details over here