The Between The Sheets first appeared as a gin cocktail in 1929, but was rejiggered, as it were, in the 1939 Gentleman’s Companion (funny and informative book) as a variation of the Sidecar while drinking at a bar in Jerusalem.
The split base of Cognac (or Brandy) and Rum was sometimes a split of Gin and Rum, Cognac and Gin, or Cognac and Rum. These variations are Numbers 1, 2, and 3. We are doing #3, but with a gold rum, ideally column still, to avoid stomping all over the Cognac.
This is a rich drink, and can be dialed in with more or less Cointreau and lemon juice.