Nice work Richard. See also here:- https://tasmanianinsectfieldguide.com/hexapoda/insectsoftasmanialepidoptera/superfamily-geometroidea/geometridae-loopers/genus-dichromodes/dichromodes-confluaria/ I've saved your image of the underside of D. confluaria in the sample imagwes of the species.
I recently got an underwing shot of Dichromodes confluaria. See sighting 4718849 has upper and underside images. Confirms this as Dichromodes confluaria.