Playing with the idea of using a hub motor as a load (vary regen) for a modern smart trainer. Thinking even a small hub will be safe at high (1- 1.5KW) loads given the average riders power output- duration. Main concerns, are how stable the load can be made given the heat and inefficiency issues as well as to how to actively control the brake load force via gps route data or third party software. May also make a decent charge station to bring camping if you bring enough food to power it. Here is a high end one that looks to have a hub motor but does not generate any useful power.