Question about vSAN and data

We are standing up brand new ESXi 6.5 hosts with 4 nics (2 10gb, 2 1gb) with vCenter running vSAN. Our old equipment is running on 5.0 and connected to storage via SAN (iscsi). I'm trying to come up with a method to get the old data to the vSAN datastore. I can't add the old hosts into the cluster as vcsa 6.5 won't allow it. I'm thinking I will have to connect the hosts to the SAN, that way the hosts will have access to both datastores and I can just do a storage vMotion. How's that sound?All of my hosts are on different subnets as well. Old hosts are on a 7.x.x.x | New hosts on 77.x.x.x | Old iscsi is using a 172.x.x.x and configured to not allow communication from either of the host IP's. The vSAN network is setup to run on the 172.x.x.x network (10gb ports). I think I'm overthinking this, but wanted to get some second opinions as this is a first for me.
Comments
"Simplify, then add lightness" -Colin Chapman
Thanks for reply. I tried joining the 5.0 hosts to 6.5...no go. Unable to manage them.
My next idea is to connect the 6.5 hosts to the SAN via iscsi and transfer the data over. I'm open to other suggestions/recommendations.
"Simplify, then add lightness" -Colin Chapman
Just make sure the datastore are VMFS 5 and not VMFS 3 as they won't be seen in 6.5.
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