Recommendations for "Standby" Host / creating an additional datastore / system partition

My ESXI 5.0 host, together with several VMs in the datastore, resides on an aging 500 GB drive.

I have a spare 2TB drive that I would like to partition for as standby host and another datastore containing the VM's, with the thinking being that when the 500 GB drive fails, I can boot from the 2TB drive and have everything running again.

I am seeking suggestions for the best option to set this up.  Thoughts include:

1. A fresh install of ESXI on the 2TB drive and restoring the configuration from a 'vicfg-cfgbackup' backup of the 500 GB host
   1. have two VFMS partitions, one a "backup" of the current datastore containing the VM's on the 500 GB drive, and the second being a 'general' ~1.5TB datastore  that I can use for a FreeNAS volume; or,
   2. have one larger VMFS partition,
2. Partition my 2TB drive to allow for future installation of ESXI; and two VFMS partitions (one the same size as on the 500GB drive, and the second using the remaining space available), or a single VMFS partition

Proceeding with option (1) would result in two drives with ESXI hosts on the one machine, but presumably, since they are not clones, the UUID's should be different so there would not be any issues with both disks being active.  I just need to set BIOS to boot from the correct disk.  Have I understood this correctly, and if so, are there any other potentials issues with this approach?  Does the ESXI install process allow for the multiple VMFS to be created on the one drive, or is this done manually via the command line interface, or vSphere client

Is the second approach possible, and would I partition the disk the same as the 500 GB (ie multiple LinuxNative partitions, a systemPartition, a vmkDiagnostic and a vmfs partition), with an additional VFMS partition (or one large VMFS partition)?  Or is it not possible to install ESXI onto a disk with some partitions that are to be retained.  From what I've seen, it seems if the installer finds that the drive has [a] datastore[s], then the option is provided for upgrading, so maybe it is possible to install ESXI on a drive with pone or more VMFS datastores on the drive..

Or perhaps there is a third option that would be best.

Any advice?