I am now investigating another approach, using one of the TP-Link “travel routers” for £17. This goes ethernet to wifi, and if it supports adhoc wifi that will do it (the tablet can do ethernet).
Whether the device (or any other similar device) actually supports adhoc wifi seems impossible to discover without buying one and trying it… It certainly cannot bridge adhoc wifi to infrastructure wifi (it turns out that many people have been down that road, with android tablets not supporting adhoc wifi) but it might do adhoc wifi to ethernet.
I did look into flashing the tablet with Cyanogenmod but the support is barely a few weeks old, so lots of stuff won’t be working properly.
