Rock-Rocker, I would not worry about the pinion being too small. At 4.88 the pinion is still very thick.
I am running 5.38's and have snapped the rear D44 axle shaft, but the pinion did just fine. Honestly, I have rarely heard of anyone snapping a pinion, even 5.38's. Others may have different stories, though. Usually, it is the axle shaft that goes first. You should be fine with 4.88's, unless you are attacking Moab like a monster truck on Red Bull & Crack.
2008 2-dr Rubicon, auto,
RK 2.5" Max Travel, Rancho 9000XL shocks, 37" Nittos, 5.38's, RR skids, Warn VR8000-S.
RIPP Gen 2 Stg 2 Supercharger.
Political Correctness offends me.