For anyone trying to do the same/similar thing:
I've had a job logged with VMware for a while now and it's just been escalated to the engineering team who have advised me there is no SSO support in the Blast Secure Gateway. So this does not appear to be possible at this point in time.
I have responded asking if it's scheduled to be included in a future update but I am guessing they probably would've advised that if that was the case.
I have also asked if there is a way we can request the feature be added. So I suspect feature requests may be the only way we can get SSO support in the Blast Secure Gateway.
Essentially, at this point in time there is no SSO support included in the Blast Secure Gateway in View versions 5.2 or 5.3. This is of course referring to providing credentials to the gateway from another source, not referring to SSO between the gateway and other View servers/services.
Cheers,
Matt Keelan