I tried Foxfi today and it worked! I'm able to use my phone to set up a Foxfi hotspot that my CC and my laptop can connect to, allowing me to cast from my laptop to my CC. I don't normally need an app like Foxfi to use my phone for a hotspot since my phone is rooted and I have the entitlement check set to allow hotspots, but the CC would not connect that way. When I tried it with Foxfi it did work, although the free version of Foxfi times out after a while. I went ahead and purchased the full version of Foxfi and was able to use my CC on a tv where there was no wifi to connect to, only the hotspot created by Foxfi. I tested casting Chrome tabs, my desktop, and a YouTube video, all successfully.
My phone is a Motorola Razr Maxx, Verizon unlimited data grandfathered. I am running a custom rom that has the entitlement check enabled, but I don't know if that has anything to do with my success with Foxfi since it does not require root. My CC firmware version is 13300.