A quick read of page 27 in the KX2 manual told me almost all I needed to know. Lacking mention is the reason for the 4-second idling time after each transmission. The manual explains how to defeat it (by sending IM with no spaces) but why is it implemented in the first place?
Tuning RTTY signals so that they decode properly takes a bit of finesse and I confess that, after an hour of tuning various stations, I still don't know how to do it quickly although it does seem to work best when the filter is set to minimum bandwidth (150 Hz).
I ended up working several stations in the contest and recorded the 2nd of them (below).