Two methods to accommodate hang distances that are too short for whoopie slings
One using a continuous loop at the ends of the hammock and bypassing the whoopie slings entirely.
The other doubling your whoopie sling back on itself and girth hitching both the adjustable and fixed eyes on the hammock and putting the doubled over whoopie sling behind the MSH on the tree strap. This can be repeated multiple times, each time halving the length of the whoopie sling.
With both methods, you lose the adjustability of the whoopie slings. However, you can move the MSH up and down the tree strap to change the length if needed.