Any gold investor would refuse to invest in such fund, because you don't own any gold, only a "promise" to maintain the peg to gold.
I had an idea to do passthru UIA for high dividend stocks in the US, the dividends would constantly increase demand for BitUSD since I'll have to buy BitUSD and pay to investors, but there's currently no way to issue dividends in Bitshares, so I can't do that.