Ah ok. Might need to rethink that then, thanks.
In case you missed it, are you going to connect the Pi (with emoncms) to your main network via an ethernet cable? If so then you could set the Pi up in AP mode and bridge the networks i,e, IoTaWatt -> WiFi -> Pi -> Ethernet cable -> network. If you were not going to connect it to the main network then either use the Pi in AP mode or get a cheap WiFi AP (completely isolated network for the IoTaWatt & Pi ) which would do the trick as well.
Just a thought. Multiple EmonTXs would be a PITA I’d suggest… YMMV.