This bit rate calculator is helpful.
If you are not stuck with standard rates (e.g. 115.2k, 230.4k ...) then 16MHz has some UART rates (125k and 250k) without framing errors. I have started to use a 12MHz crystal on ATMega328p at 3.3V and it has those rates also, it is able to talk to the other ATMega328p over a long differential (RS485) pair at 250k bit rate. I have an idea that avrdude works at those non-standared rates but I have not verified. Unfortunately the program (picocom) I use on Ubuntu and Raspbian does not work with non-standard rates (picocom was fixed but it has not been pushed into Debian).