NAT Public IP to Policy Based VPN

I have multiple IPSEC VPN connections to client sites.  Most are route based IPSEC, but have been forced to switch to policy based VPN due to limitations of maximum static route definitions required by route based VPN.  I have the requirement to NAT a public IP address on my firewall to allow access to a web service on a host on the remote side of an IPSEC VPN.

Have not had any issues in the past with creating a NAT policy when using route based VPN as the rule specifies source and destination interfaces and I get to use the virtual IPSEC interface as the destination.  Can't seem to find a way to route the WAN IP address through a NAT policy using a custom port back out through the WAN over the policy based IPSEC to the remote server.

Is such a thing possible?