While direct "unicast over multicast addresses" isn't possible as Ron has pointed out, it should be possible to tunnel unicast over a multicast network or, in another perspective, create an unicast-enabled overlay network on a purely multicast one.

You "just" need to find a tunneling protocol that supports multicast destinations, regardless of (unicast) source addresses (which you could - possibly - NAT statically). I'm not at all sure if that even exists but with sufficient effort, it could be created.

While direct "unicast over multicast addresses" isn't possible as Ron has aptly pointed out, it should be possible to tunnel unicast over a multicast network or, from another perspective, create an unicast-enabled overlay network on a purely multicast one.

You "just" need to find a tunneling protocol that supports multicast destinations, regardless of (unicast) source addresses (which you could - possibly - NAT statically). I'm not at all sure if that even exists but with sufficient effort, it could be created.