All the mechanics in the world won't help you if the fundamentals are broken.
At some point, when push comes to shove, someone has to take delivery of something. This comes down to a matter of efficiency and faith. Who do you have more faith in? A random bank claiming to having a certain amount of gold on deposit? Your own central bank taking in tons of gold for delivery of a good?
This is silliness. If the USD is inflating too much (or if you perceive American sanctions as too onerous) then use a different currency like the Swiss Franc or the Euro.
None of this really matters. What matters is international settlements, agreements, and force. If you're on the wrong side of the WTO your economy is cooked anyway. Besides, if Ghana were some stalwart of anti-corruption then this may mean something, but it isn't. It's middle of the pack. Well behind Canada, Europe, Japan, and The United States; all countries or blocks that are perfectly fine selling and buying in USD.