Is there financial help when Medigap costs drive my net income too low?

I am an under 65 disabled woman and am eligible to enroll in Medicare Parts A & B Oct 1. For reasons I have discussed with my doctor and Medicare resources, I need a Medigap D plan – an MA plan with Rx benefits will not do. Because I am disabled, this plan will cost more than $500/mo. My monthly income is $1,500 before Social Security and Medigap premiums. My income is too high to qualify for Extra Help. However, after Medigap premiums, I will have only $1,000/mo to live on and that is before I buy a Part D plan. How will I survive? There is no place on the Extra Help Application to describe this situation. What do you recommend?