One of the most knowledgeable blokes on icing in GA twins is a bloke by the name of Lance Scott. He spent a fair bit of his time flying Chieftains and Bandeirantes in Tasmania for Air Tasmania and Airlines of Tasmania then did a stint flying BSF a Pressurised Navajo on rain making for Don Wells over the Victorian high country.
Plenty of blokes at Airlines of Tasmania were lucky enough to have Lance pass on his knowledge on icing, how Chieftains handled ice, escape plans and techniques to use when encountering ice etc.
Considering that Airlines of Tasmania had a fleet of Chieftains and Herons that did not have any de icing boots or weather radar, and they operated RPT out of Hobart to Strahan with a LSALT of 6800', Launceston to Hobart on the nightly paper run, TNT freighters out of Hobart to Melbourne in Chieftains, Launceston to Flinders Island with a LSALT of 6100' along with with charters to places like Canberra etc. Lances experience and knowledge on ice was of great benefit to us newbies.
Plenty of industry gurus will prattle on about ice, but when you ask a question or two, you realise they either don't have a real lot of experience in icing conditions or their knowledge is gained from the met book. Plenty of IFR instructors have never seen ice, but will happily tell you all about it!
The old story about the grand military pooh bar, who showed every one how good he was(after all the military pilots are the best) blasting off in a Baron out of Canberra on a very nasty day with a segment for severe ice and a low freezing level! Apparently the Baron doesn't perform that well covered in ice and at full power below the high LSALT around Canberra, something was mentioned about going via a different route with a lower LSALT, but the military man was a proud man and decided to go with the route as planned. After all military aviators are the creme de la creme!
I don't agree with your theory on underwing ice on the DC-3 at Hobart Centaurus, normally Hobart wouldn't get that cold for ice to form. Wasn't the accident supposed to been caused by cargo shifting!
Last time I saw Lance he was chief pilot for Heron Airlines, but then I had heard that he retired back to Hobart and was doing some casual work for Don Wells.