Make it handle

[BMERDOC]

Rob, That much caster will cure just about any abnormal tendancy. I think your biggest problem would be what I call "trameling", bumpsteers ugly little sister. A wide/low profile (or just wide or low profile tire) has a tendancy to follow defects in the road surface. The wider or lower a tire the greater the chance of this occuring. I think that a greater amount of caster would help in correction but wouldn't help in the initial response of the tire to the defect in the road.
With that much tire and caster, even with power steering, I hope your gym membership is still in effect
Are you concerned about unsprung weight?