Change the rescanhba timeout

ESXi 5.5 host has 3 old Dell MD series arrays on iscsi. Since MD boxes don't play well with anyone else, or even with themselves, per Dell instruction, each nic on each controller gets assigned it's own individual class C subnet. Best is to have a dedicated nic on the server as well, but that part can be worked around.  The issue that all this creates, is when rescanning the HBA for volumes.  Since I now have a host with 14 subnets in the dynamic device list, it takes a measured 34 minutes to rescan.  During this, I get a timeout error from vsphere.  It will eventually finish the job, and find new volumes just fine, but the timeout is killing my SRM deployment.  I am using storage replication, so SRM needs to handover the active volume, then tell the host to rescanhba to pick up the activated volume replica. The handover happens fine, but when the timeout error comes back to SRM during a test, (or recovery) it aborts the operation saying the storage could not be found.

So I am looking for one of two solutions.

1. change the timeout parameters on both vcenter and SRM to allow (much) more time for the rescan to finish.
2. find a way to shorten the rescan. Note I have been days working with Dell and VMware trying to find a way to do this, so I don't hold much hope here.

Ideas?