In theory yes, but in practice problematic. You’ll have trouble setting up a client to accept/offer the restricted list of old/bad ciphers that trial FortiGate VMs are limited to. (AFAIK SSL-VPN is still subject to these restrictions; corrections welcome)
It’s not possible since the versión 6.1. Before down de SSL cipher and now it’s not job this workaround. You need license, I was test in VM and appliance.