Those are some nice hints.
There seem to be several DisplayLink adapters out there. But I end up on the thread about OTG and ACA, which you probably can recall. Which leaves me on the power front and surely would be a bummer, and the struggle with compiling my own kernel with my little netbook and a limited 4G blows the rest out of this project.
Or did you ever dig deeper into the ACA hustle?
A P2P dongle together with a bluetooth keyboard seems the way to go, and hoping for reasonable lag…enough to write some texts.