Just throw away the echo Rx character each time you transmit a byte. I've done this on both the PC side and on the MCU side without problem and with very little overhead. As you've noted, the echo character is only a concern when you're transmitting characters.
I am throwing chars away currently but as there are lots of places where I send characters it's a lot of code overhead, I thought there would be a way of sorting (blocking) the RX when TX'ing using a line driver / buffer or something