Are there any known low-inclination trans-Neptunian objects?
Queries to the JPL Small Body Database or the ESA Asteroids Dynamic Site for such bodies return several results.
Some of the bigger ones are:
Centaurs with H &lt; 10 and i &lt; 4°

386968 (2012 BR61), q = 11.7 au, Q = 31.6 au
527328 (2007 TK422), q = 17.0 au, Q = 25.2 au

TNOs with H &lt; 5 and i &lt; 2°

119951 (2002 KX14), q = 37.3 au, Q = 40.9 au
42301 (2001 UR163), q = 36.8 au, Q = 66.4 au
48639 (1995 TL8), q = 39.9 au, Q = 65.0 au