I don’t think you will find much of use in those links, I couldn’t anyway, sorry FC.
I have a book about Cruiser HK33 which was a German commerce raider which operated in a similar manner to the British Q-Ships. Written by HJ Brennecke “Ghost Cruiser HK 33” published by William Kimber 1954. The ship was also know as ‘The Pinquin’.
Sadly there is just one rather distant shot of her and a stern quarter view as frontis piece. I know from the book that she changed her profile from time to time to avoid alarming her victims and she looks somewhat different in the two shots ….
I’m pretty sure from reading way back that one or more of the Q-Ships was a wooden sailing vessel who when the sub surfaced to sink her by gubfire .. torpedos were expensive and limited supply aboard …a ‘panic crew’ would abandon ship hoping that the U-Boat would close for a closer look and be sunk by the gun crew left aboard. The Q_Boats gun was disguised as deck cargo, timber, which folded down for action.So I guess you could use any small ship of the period and midify it as did the crews .