A 29 mile cruise can't be any worse than light traffic. Does it overheat in light traffic?
I think electric will be more than adequate, they've been used in production vehicles for some time now, but if doing away with the mechanical fan, go with dual electric fans. Mechanical fans don't really break; typically, if they do, there are bigger problems. Electric fans quit without warning. Having two ensures that there will be some cooling if the other fails, and should give you reasonable time to notice.
Lawrenceville, GA