Confirmed via the great folks at the RadioReference skip/tropospheric ducting forum - I am now able to confirm a signal that I'm hearing every time the band is open - 32.180 MHz FM with 77.0 Hz CTCSS. Spanish language taxi dispatch lady YL dispatcher.
32.1800 MHz FM - 77.0 Hz - Alajuela, Costa Rica Taxi Dispatch - confirmed use
32.1800 MHz FM - 141.3 Hz - Alajuela, Costa Rica Taxi Dispatch - confirmed use
Also 31.2000 MHz FM - 203.5 Hz - Spanish speaking taxi dispatcher - apparently this frequency/tone/user has been logged since at least 1988. 31.200 MHz FM 203.5Hz is still active, I last heard it myself a couple days ago - the same time that 32.180 MHz was coming in very strongly and the 27.5-39.5 MHz Dedicated Fisheries Radio VHF low fishing fleet chatter out of Asia was coming in on 29.775 MHz FM, 30.300 MHz FM, 30.775 MHz FM, 30.900 MHz FM, 31.100 MHz FM, 31.800 MHz FM and other frequencies.
I did some more searching, and a lot of folks have monitored these comms, including on 29.875 MHz FM, and numerous additional frequencies in the 30-35 MHz portion especially, all with the 25 kHz channel steps, and never with a CTCSS or DCS tone/code.