This should be achievable - using following 2 things:
1. 'same-security-traffic permit intra-interface' command
2. create a NAT statement so that ASA proxy ARP for the public ip address on inside or dmz or any other interface:
For dmz users, the source and destination will be behind the same interface, so U-turning will be needed.
NAT(dmz,dmz,) source static <real ip> <mapped ip>
For users behind inside,
NAT(dmz,inside,) source static <real ip> <mapped ip>
corresponding ACL might be needed.
Please try and test it out.