I presume you were running HF SSB?
If you run CW you have no choice - you will be automatically spotted by the RBNGate Robot (unless you don't post an alert). So self-spotting, somehow "balances the playing field" for SSB operators as RBNGate doesn't work on SSB signals. That said CW Ops also self-spot at times.
You don't have to self spot and when I was living and activating in Australia, often I would not need to - I would simply call CQ SOTA on 7090 or 14285KHz and I would get contacts - one of whom would spot me.
As you have found, in Germany, calling on an expected frequency is often not possible as some Italian or Russian (or other nationality) station is often sitting on the common QRP frequencies chatting with his mate down the road, both running QRO power levels that are not even allowed in Germany. So one has to search for a clear (often at an odd part of a band) frequency that is free (at least it's free until you have finished your CQ call on it). To inform the chasers that you are on a wierd frequency, I think self spotting is the only option.
I see you said it took two activations to get the required 4 contacts for the summit points. I'm not sure if this is correct. As the activations were on two different days, I think they stand alone. It's not like the WWFF rules where you can accumulate the required 44(!) contacts over multiple activations.
APRS could be an option. On VHF it should work from an APRS equipped 2m HT from some summits. I know HF APRS exists but I don't know of anyone using it from a SOTA summit, most use a smart phone or SMS using a handy.
I see you are not located too far from me (I live near to Landsberg am Lech) if you want to do a joint activation sometime, let me know. (Naturlisch, mann spricht Deutsch auch, trotz meine Englische nationalität).
73 Ed DD5LP.