So it's not recommended to so this with 2 ESXi hosts only? Why do you recommend 3?
Note that when you to perform an upgrade of one of the ESXi in a 2 node cluster you will be running temporarily without protection for your VMs', meaning all your VMs will be moved onto a single host runs without a fail-over host.
Hence recommended to go with 3 as the minimum. Nevertheless, two works fine. 
~dGeorgey