ERISA Section 3002(b) provides in part as follows:
QUOTE
The Secretary of the Treasury may waive the imposition of the tax imposed under section 4971(b) of such Code in appropriate cases.
IRS Revenue Procedue 81-44 deals with the waiver of the 100% penalty of section 4971(b), but there is no mention of waiving the 10% penalty of section 4971(a).
If you are going to pursue a waiver, my recommendation is that you get your fee paid upfront.