You had mentioned "setting it low for transmission" which is what you would do if you wanted inverted 8N2. The hardware uses true (idle high).
38400 is the baud rate. I like the idea of using the pacing, but I am pretty sure that the SERIN / SEROUT combos are limited to 19200 max in terms of Baud Rate. 38400 is easy with a hardware UART and a 20MHz crystal.
You could: DEFINE OSC 10 but use your 20 and get 38400 out of SERIN and SEROUT. IF you do, watch your other timing issues like Pause (see section 7.1 of the PBP manual).