6to4 tunnel over

[jdMobius-IT]

I have many clients that I have connected via ipsec. Each client receives a virtual local IP via this connection. I was able to set it up in PFsense, even if not so nicely.
But I fail with the 6to4 configuration.
I cannot enter an IPv4 address as the "GIF tunnel local address", the interface wants to force me to set an IPv6 address. I set the routes for the tunnel manually.
How can I map the configuration in PFSense as in my Linux example?

iface 6to4tun inet6 v4tunnel
        endpoint  6.6.6.6                                                               
        address 2001:db8:bebe::2:1/64
        local 172.17.0.2
        mtu 1280

The Gateway is a Mikrotik
the configuration:

/interface 6to4
add !keepalive local-address=6.6.6.6 name=Name remote-address=172.17.0.2

I fear that I will have to replace the PFsense appliances with Mikrotiks for my customers because this configuration is not possible ...
But maybe I just haven't found the right settings yet.