Like I do, I got to thinking how I could achieve this whilst portable (limited propagation potential from my home location). So I dug out an old 4-port router with Wifi (Add-NWR9500) and hooked it all up to that. This worked well UNTIL I unplugged the internet link from my shack router at which point the ADD-NWR dropped my phone off the wifi.
A friend in my local club (Pat, G4FDN) who is a whizz with networking stuff suggested that I try one of his mini-wifi boxes, in particular he lent me a GL-inet GL-MT300N-V2.
Hooking it all up and bingo, it streams from my phone to the pluto and weighs next to nothing.
Seems a shame I can't config something inside the ADD-NWR to ignore loss/lack of internet but I wouldn't know what to look for - any experts out there?
It's fine once hooked up and working, but seems to need a reboot (Pluto and/or router) now and again if the phone drops off, like when I wondered if it would do a 4G hotspot while streaming - it won't! Now to try my simless Nexus 5 'radio apps' phone and see if it will stream Larix too

All good stuff!
*** EDIT And it works with my old Nexus 5 too, and I can film at night as the camera light can be controlled from Larix

*** EDIT AND its got audio too.....
Gareth G4XAT