Counsel should research to satisfy their "low risk" determination.
The IRS, as far as I know, does not look at degrees of risk.
The IRS focuses on games of chance and whether money is required to enter one. If so, they say those funds aren't deductible. Sure, what's described here isn't "gambling" from a State perspective (states set gambling laws). But it could be a game of chance that renders the requisite payment not deductible.
USLegal,com defines a game of chance in part like this: "Games of chance are those games whose outcome depends upon an element of chance, even though skill of the contestants may also be a factor influencing the outcome."
I found this in paragraph 402.211 of the Texas Administrative Code: "(1) Game of chance--A game or contest that awards a prize and whose outcome is determined, at least in part, by the element of chance or luck."
I agree with your attorney that what's proposed here isn't gambling, but it seems to meet the definition of a game of chance (but I am not a lawyer). Donors are making payments in the hope of winning something.
You all need to decide whether to treat these as tax-deductible gifts or transactions that have a "low risk" of being considered something else.
If it were me, I'd not claim these payments were tax deductible and instead treat the effort as a "proceeds to benefit" activity. Then, you run no risk.
John