Necro'ing this topic but I thought I'd post the solution.
I was stuffing around with ILI9341 displays on an Arduino Pro Mini but couldn't really get them to work properly at 115,200 baud, even if I increased the serial buffer to 1k.
Instead, I got a NodeMCU v1.1, and installed the excellent ESP-LINK firmware on it.
I now have a serial console via Wifi to the Mysensors controller with close to zero effort on my part.
The only change I needed to make (on the Sensebender Ethernet Gateway) was the following line to direct the output to the serial port in the MYSX connector:
#define MY_SERIALDEVICE Serial1