First of all, I would apply for a DTV visa. You can refer to your wife's income, but they usually grant this visa for hospital treatment as well, of course with the appropriate hospital documentation. But the first option might be good. They don't look at the 500 thousand per person, it's enough if your wife does it, and if she gets a visa, you can apply for the rest with a sponsorship letter in which your wife writes that she will cover all the costs incurred abroad.