Thanks for that insight, Eurotexan!
I own a home and have h/o insurance, but no auto insurance due to no auto owned.
One of the agents I spoke with (one that quoted me H/O, non owner auto, and umbrella together for $1100ish) mentioned that with standalone umbrella and no auto policy, the umbrella will not cover any event related to an automobile....In the absence of an auto policy, I would pay ~$20 per day for $1million liability insurance at the rental counter.