My solution would be to make it so the company that fires you has to cover you for say two months at the same rate (as they did in the past). If a previous company covered you, then the new insurance company has to cover you. If you never had health insurance, then !@#$ you.
Further edit - Companies shouldn't hire temps so they don't get benefits (some temp agencies provide insurance, but not all). A period in which the person doesn't get benefits should be disallowed as well. You aren't sure you want the person and willing to give them benefits, don't hire them. If you decide to fire them, suck it up.