To give you smoe clarification on your question:
A VS lives on either of the physical cluster members, when either fails it will automatically move to the other box.
VSLS is a different form of VSX clustering and allows you to define where which VS will be running.
You cannot put 2 VS's in a cluster. In other words: You cannot use a VS as a cluster member.
As soon as you put the 2 physical gateways in a VSX cluster you define the way you want to work for that specific cluster, either HA or VSLS. Whichever you choose, there will always be a shadow VS on the other cluster member. Transparent mode (bridge mode) does not change that.
Regards, Maarten