RS-232 Tx / Rx monitoring LEDs?

[drlegendre .]

As part of my C-64 RS-232 to M15 60mA CL project, I've put together a
simple MAX232 based interface to connect the TTL levels on the C-64 to the
standard RS-232 +/- levels.

Is there any reason that I can or cannot install LEDs - on either side of
the MAX232 converter - to give some indication of line status?
Specifically, a pair of LEDs, one each for Tx and Rx lines, to blink / etc.
as line status changes and data moves.

I don't see any obvious issue - but I can conceive of a situation where it
might screw up the line in some way I haven't considered.

Comments?