To the specific question of medical insurance
for traveling and expatriates, there are policies offered specifically for that purpose. They cover you only when out of the country so don't duplicate other coverage. They can be for one trip, for infrequent travel or for those living out of the country, such as cruisers.
The other possibility is high deductible riders or major medical
. These would not cover any routine care but would provide protection in the event of a major illness or surgery.