ipnat rdr with bimap?

I am not sure I can do this...here is my current ipnat.conf:

bimap bge1 192.168.1.11/32 -> 207.227.112.11/32
bimap bge1 192.168.1.12/32 -> 207.227.112.12/32
bimap bge1 192.168.1.13/32 -> 207.227.112.13/32
bimap bge1 192.168.1.14/32 -> 207.227.112.14/32
map bge1 192.168.1.4/32 -> 207.227.112.10/32 proxy port ftp ftp/tcp
map bge1 192.168.1.0/24 -> 207.227.112.10/32 portmap tcp/udp auto
map bge1 192.168.1.0/24 -> 207.227.112.10/32

....I have 2 web servers
192.168.1.13
192.168.1.14

I want to use round-robin (or something) so that I have a vaild
failover in case .13 or .14 is offline. Setting up DNS to point at
both doesnt take care of this problem.

Can i use 'rdr/round-robin' with bimappings?

the idea here is that DNS will point www traffic fixed at
207.227.112.14, but I would like to see if ipnat can send that to
either machine - especially if one is offline.

Possible?

-JD