IPhone 6 Hotspot vs VPN

[hawker9000]

I would like to be able to use my Roku3 here in Thailand by connecting to my iPhone 6 via Personal Hotspot and Witopia VPN. Witopia has advised that the iPhone will split-tunnel devices connected to it via the Hotspot, and not send that traffic through the VPN tunnel. (And that's necessary for the Roku to be able to stream certain US-based services like Hulu or Amazon Prime, because those services need to see US-based IPs).

Does anyone know if there's a way to get the iPhone to make ALL traffic, incl hotspot traffic, use the VPN? Witopia just uses native IOS VPN setup configuration, not a separate VPN client (like it does for Windows). So, a third-party VPN client perhaps?

[hawker9000]

Update: Witopia does offer a separate client for OpenVPN. It's a bit labor-intensive and involves creating a configuration file on a pc which then gets uploaded to the iPhone along with client software. But I see no evidence that this might address the split-tunneling issue I need to deal with. 'Have also seen discussion of IOS 9 having "broken" OpenVPN functionality.