"Yep there is actually a pretty big gap between these objects and the next largest dwarf planet or moon"
I am not sure what you mean by that. My impression is that they all clump up together, very often with changes in order. On that basis I will continue the list, but please don't tell me there are errors. The order keeps changing with new/improved/whatever measurements:
After,
Haumea 1960 km
Titania 1577 km
Rhea (Saturn V) 1527 km
Oberon (Uranus IV) 1523 km
Iapetus (Saturn VIII) 1468 km
Makemake (136472) 1440 km
2007 OR10 (225088)
Charon (Pluto I)
Umbriel (Uranus II) 1169 km
Ariel (Uranus I) 1158 km
Dione, (Saturn V) 1123 km it continues
Quaoar (50000) 1070 km
Tethys (Saturn III) 1062 km
Sedna (90377) 995 km
Ceres (I) 934 km / 952 km / 914 km take your pick
2002 MS4 (307261)
Orcus (90482) 917 km
Galacia (120347)
2002 AW197
Varda (174567)
2013 FY27 (532037)
2003 AZ84 (208996)
Dysnomia (Eris I)
Ixion 650 km
Enceladus (Saturn VI) 504 km
Miranda (Uranus IV) 471 km
Porteus (Neptune III ) 420 km
Mimas (Saturn VII) 396 km
Hyperion (Saturn VIII) 360 km
Nereid (Neptune II) 340 km
Amalthea (Jupiter V) 250 km
Phoebe (Saturn IX) 213 km
Janus (Saturn X) 203 k
Larissa (Neptune IV) 194 km
Galatea (Neptune VI) 176 km
Himalia (Jupiter VI) 170 km
Puik (Uranus XV) 154 km
Sycorax (Uranus XVII) 150 km
Despina (Neptune V) 148 km
Portia (Uranus XII) 135 km
Thebe (Jupiter VII) 116 km
Elara (Jupiter VII) 80 km
Thalassa (Neptune IV) 80 km
Naiad (Neptune VIII) 58 km
Note I have added a few moons as I went along, but lots are missing.
After that, I haven't put any and all bodies in (believed) order, but I can give you the largest asteroids in the Asteroid Belt, with 'diameter' in km. (BUT most will probably not be spherical, so take diameter as you wish)::
Ceres 934
Pallas 526
Vesta 510
Hygiea 408 0rb430
Davida 326
Interania 316
Europa 302
Juno 268
Sylvia 260
Euomnia 256
Euphrosyne 256
Psyche 254
Cybele 240
Bambergo 230
Patentia 226
Doris 222
Camilla 222
Herculina 222
Eugenia 214
Here are some
Dwarf Planets: 'diam' km.
Eris 2326
Pluto 2306
Haumea 1960
Makemake 1440
Quaoar 1070
Sedna 995
Ceres 952
Orcus 917
Ixion 650
Cat