Andrew, I activated many summits in the “Gailtaler Alps” on 2m. Last year I had nearly the same route to Latschur (This mountain is female as many in OE8), went up for the first activation, but someone was there the day (!) before. Vy gld that I were qrv on HF. No 2m QSO as I can remember.
There is a quite active community in OE8 and S5 (some active chasers in S5). I always announced my upcoming activities via repeater the days before. Once and OM called his XYL interrupting her cooking in order to fulfill my 4th qso, hi.
The common 2m QRG is 145.550 one should know, and the local repeaters. I also had QSOs on other frequencies, eg. 145.350. And from a high summit you can break into nets from the adriatic coast, if your ant has some gain. But you cannot rely on it. It is very dependent on day of week / time of day. I had an attempt two weeks ago, and I found myself in the middle of a thunderstorm at the summit. No good idea to erect a HF-ant. Regrettably, I did not invite the local OMs - so only 2 QSO via repeater. nil direct qso. As you mentioned, not the first and for sure not the last time this will happen. That’s part of the thrill…
73 Martin, OE3VBU