DFVCP is not available to EZ filers (it is a DOL program, and DOL rules do not apply to EZ filers). The IRS has a similar program, you can read about it here: https://www.irs.gov/retirement-plans/penalty-relief-program-for-form-5500-ez-late-filers
Since you said $500 for a single filing and not $750, I'm guessing you are already aware of the IRS program, but were just referring to it by the wrong name.
Strictly speaking, the IRS program is a penalty relief program; so if there is no penalty to relieve then I am not sure you are eligible for it.
However, if you went ahead and filed under the program anyway for all years, I think it's likely that they will just cash your check, stick your returns in a box somewhere, and never think about it again.