If you're 172.16.X.X is a flat /16 and that's the only network the customer server needs access to, then I would think a simple PBR ACL on the network hub switch would suffice... According to the subnet masks you have in your diagram everything else would be L2 switched... If there are additional subnets at your hub site that the customer server needs access to, then more specifics would need to be added to the policy.
So something to the effect of:
entry PBR {
if {
source-address 172.16.10.10/32;
destination-address 0.0.0.0/0;
} then {
redirect X.X.X.X (the appropriate next hop for the remote site)
}
}