I don't really see the need for trimming with 275/70r18's. Reason being, my BIL put 295/70r17's on his Big Bend (mind you he did the 2" leveling kit), and all we did was remove the crash bars, doesn't rub at all (at full turn). Throw in the fact that tire is wider than the 275/70.
2021 Broncos - BaseSquatch 4dr. Rapid Red V6 Soft Top
Big Bed 4dr. AMB V6 Soft Top Tow (BIL's)
Nitto tires SUCK! You've been warned.