FGVM Cluster in vCloud Director without Promiscuous mode functions

[FjordNestor]

Hi,  We have 2 Fortigate Virtual Edition appliances that we want to cluster together. The environment we're in is vmWare vCloud Director 5.1 hosted by a provider. We know that to cluster 2 Fortigate VM, we need to set the virtual switch in Promiscuous mode for the Cluster to work. Unfortunately, our provider does not allow us to configure the virtual switch in Promiscuous mode from the vCloud Web Interface and he does not want either to configure the Virtual Switch inside vmWare because it may affect other clients running in their Cloud environment. We are on a dead end to set up Fortigate VM in HA (Active/Passive) because of this. Is it mandatory to have Promiscuous mode configured on the virtual switch? Is there other configuration options we can work with? Thanks for your help!

Sylvain