I'm attaching my edited version. Ended up mainly using Rich's suggestion, with a little additional adjustment brush, because for some reason, the CA tool did absolutely nothing for me. Is this an unadvertised difference between LR4 and LR5? In any case, I'm pretty happy with the result (although I'm still playing with the right PP to capture the feel of the place -- this is the sort of shot I've yet to really figure out how to PP).
Thanks again, all!