Honestly this isn't as easy to do as you seem to be hoping.
At a minimum, it's an entirely enterprise solution looking to be implemented in a small business budget.
Site-based DR is really what "replication and SRM" is all about. FT really is aimed at "my server failed and I'd like to fail over to the server sitting on top of it".
Edit: The P4300 can to live mirroring. Again, this is based on the idea the san components are next to each other. It's not even supported to have the two units on different subnets.
The "site mirroring" functionality involves an artbitrator to do a failover, this is not a "live" solution that will support FT.