When the similar issue arose in our environment, we put into use Veeam Free Edition with its Quick Migration functionality which allowed us to migrate promptly several VM between ESXi hosts/cluster.
Since we were moving VMs between hosts with compatible CPUs, VB&R used SmartSwitch technology. This technology suspended VMs only for short period of time and later VM was resumed on the new host. Using such scenario guaranteed for us minimum downtime (much better than simple cold migration, actually).
So, all you need to do is to add both hosts to the VB&R console, choose corresponding VM and perform Quick Migration. Works like a charm.
Thanks.