Trail Run Race Training on the Big Island


We will be visiting the Big Island in early August this year, only a few weeks before the Leadville 100 Trail Run that I'll be competing in again this year. I'd like to squeeze in a 20-mile trail run while in Hawaii, but I don't know the trails and there seem to be no organized events scheduled for the time that we are there. Does anybody know of long-distance training runs or a nice 20-mile (or so) trail route I could run? I'd really appreciate some help. Thanks!