Rather than elimination of the estate tax, why not a referendum mandating disposal of public lands? Perhaps setting a "cap" of 20~25% on public ownership (allowing some for legitimate use for public parks, nature reserves, etc. etc.).
20~25% too high/low? Suggest a percentage that you think reasonable.
Please don't insist on 0%. That would be extremist and absurd.
Better yet, why not both?
Why should the government be ANYONE'S primary heir, regardless of whether they are "rich" or not?