>There’s also no evidence that Northern Europe or Central Europe had developed sailing to the level of sophistication needed.

That is such nonsense. People in Bronze Age Scandinavia, the British Isles and Northern Spain were all seafaring people. Especially in Scandinavia, where they had ships decorating almost every rock art piece one can encounter from those days, had burials in ships, etc.

The Tollense Valley Battle shows that large scale conflict existed in Northern Europe.

Mercenaries from the North went South to gain riches fighting (that's why there's many objects of Northern origin in the Mediterranean and Mediterranean objects as far as modern day England, all in the Bronze Age. Plus, people DID carry Tin from England as far as Cyprus) and then returned home, this is not only attested by material and genetic evidence, but also sources that immediately followed the Greek "Dark Ages".

All this together, I don't see why you see it as "impossible" that the oh-so poor and unsophisticated (/s) Northern and Central Europeans couldn't been part of the Sea Peoples coallition. Especially when the depictions of the horned warriors from Medinet Habu match the various rock art depictions and decorated Menhirs from Scandinavia to Spain and even in Sardinia.

You seem terribly biased on this subject.