Using snapshots is good idea. However, I don’t thing this method would be considered amnesic since data is written to Virtual HDD not VRAM like Whonix live mode
I would not use this method if an amnesic feature is requried.
In lieu of the above method, I would wait for Whonix 14 (Whonix live mode)
The Whonix Live package in Whonix 14 does not do too much. I guess you could just install it as well on Whonix 13, just make a snapshot before installation. Or follow the steps here: ⚓ T714 Whonix live mode / grub-live if you want to do it manually. Whonix 14 is not out yet but you can still download it. Just because it is a dev/testers version doesn’t mean it is broken (could still happen though). If you encounter any issues please report them.