OMG
"Is a Trans Victorian someone who was born in either the 20th or 21st century but identifies as having been born in the 19th? A bit like Jacob Rees Mogg? Do they campaign for their birth certificates to be changed from e.g. 1975 to 1875?" genius Rubidium GENIUS.
I totally identify as Trans Victorian.
And, although I believe your post is genius, I would respectfully argue that Victorians, with their franchise enlargement, giving women's right and rise of Trade Unions are far too open and radical for JRM... I believe he is Trans Stuart.