The whole point of the $35 an ounce gold standard was that the amount of gold that a dollar represented never floated, it was always fixed over time, and the paper note was always redeemable for real gold.
The reason we're off the gold standard was during the Depression FDR made it illegal for US Citizens to own gold, other than jewelery. He stopped the minting of gold coins, and ended the private redemption of paper notes for gold or silver.
We still maintained the $35 an ounce gold exchange with foreign governments, but in the early 70's there was a run on our gold reserves by Great Britian and others who wanted to exchange their dollars for gold. There simply wasn't enough gold in Fort Knox to cover all the foreign held notes, so Nixon ended the foreign exchange of gold, putting us on a fiat currency.
If the amount of gold that a dollar represented were allowed to float, and were not convertable in the manner you assume, the dollar remains a fiat currency and the "gold standard" as you describe would be a myth.
Sorry you misunderstood my suggestion. Actually a "floating gold standard" exists to some extent because the abilty to buy , hold and sell gold is again allowed in the USA. And there are multiple electronic gold exchanges for electronic digital gold, like e-Gold.
My suggestion was simply to point out that there *IS* enough gold to go back on the gold standard, it's just a matter of picking the fix. I would not advocate allowing it to float, once it was set. That as you point out doesn't accomplish the goal.