I had the same problem back in '88, and ended up creating my own Trace.exe
We only had DOS back then, so no fancy interface, but many features, not even found today - they may / may not be useful. eg Time stamping Rxd-Txd to uS, breaking into a serial line and setting up "packet watch" and or "auto replace" strings etc etc
I'll attach the program, it may be of use. Detailed functions are described in the Trace.TXT file. Ignore license / pricing stuff, it paid for itself many times over :-) I still have the dev system (not used it in near 20yrs, but could change things if needed). Actually, I still use the program occasionally.