MAG writes:

Unfortunately, the umbrella policies I've seen so
far seem to be very leaky.

It is supposed to cover your liability for your acts, not uninsured
motorists. Not really a "leak".

You should by all means consider the exclusions seriously, but often they
don't hold up in court.

Florida is in an insurance crisis on several fronts. You can't buy (to
save money) a homeowner's policy omitting exorbitantly-priced hurricane
coverage, because the insurers are afraid the state would void the
exclusion if there was a loss.