Rubicon Express has a hand throttle kit that may help in this situation (after you see the kit, you may want to simply buy the parts locally, however). I have a hand throttle with the bicycle adjust on the gearshift lever. It helps in the situation you describe, but is not a cure-all solution, and you still need one right and two left feet! I would estimate that I use the hand throttle maybe 50% of the time; it's fun to set the hand throttle and then slowly cruise up the less difficult mountain trails.

94 YJ, SOA, 2-1/2 Alcans, ARB-front, Detroit-Rear, 4.56:1 gears, Oasis Trailhead compressor, 4:1 Terra Lo, 37x12.50x15 SSR's, 8000 lb Ramsey, & etc.