In case you configured the domain to select it's proxy id per pair of gateways, it surely sends 0.0.0.0/0 what is expected behavior.
On the ASA side there should be something like this:
crypto map outside_map 10 match address VPN-Traffic
crypto map outside_map 10 set peer <Peer_IP_Address>
! Define the ACL for interesting traffic
access-list VPN-Traffic extended permit ip any4 any4
This is how i configured that long time ago
and now to something completely different - CCVS, CCAS, CCTE, CCCS, CCSM elite