1) NGC 7507 in Sculptor (visual 10.8, s.b. 12.9, size 2.8 x 2.7) using Expanse 6mm EP.
2) NGC 7176 in Piscis Austrinus (visual 11.2, s.b. 10.9, size 1.0 x 0.8) using 2X Barlow and 6mm Expanse EP.
3) NGC 7173 in Piscis Austrinus (visual 11.2, s.b. 11.2, size 1.2 x 0.9) using 2X Barlow and 6mm Expanse EP.
High surface brightness of these galaxies helped, along with an absence of sky glow above the southern horizon because of the Pacific Ocean. Of course there were others with just slightly lower visual and surface brightness (but were higher up in the sky) that I couldn't detect with this scope, no matter how hard I tried:
1) NGC 7252 in Aquarius (visual 11.7, s.b. 12.8, size 1.9 x 1.6) - tried on 2 separate sessions
2) NGC 309 in Cetus (visual 11.6, s.b. 13.6, size 3.0 x 2.5) - tried on 3 separate sessions
I used the stock star diagonal that came with the ST80 on all these sessions. Without having to move to a darker sky site, next time I'll use my dielectric star diagonal to see if it makes a difference. Less humid conditions would help as well.