I think that should look like this: HMO style access for all - automatically. Rebate if you decide to up it with PPO style insurance (or beyond). So you get 200 per month off taxes to pay towards your own insurance.
Also, get it out of the employers hands - as in make it illegal to offer any benefits and let the employee get paid 100% of their salary instead. Also make it so that employers can't legally collect taxes without consent.
You'll then create two systems – PPOs for the healthy that can afford it, underfunded HMO for those who can't.
Just drop the rebates, and make any secondary insurance be primary. That would make sure the insured group for the public system includes the healthy rich (which makes the pool for those that actually need and can't afford their health).
Also, get it out of the employers hands - as in make it illegal to offer any benefits and let the employee get paid 100% of their salary instead. Also make it so that employers can't legally collect taxes without consent.