Not the only way .... however, one that might save you a penny 'r two (special emphasis on "might").
It seems as if you have a full service account exec(?).
If so, ask them to find out the bid/ask on the spreads.
Not always, but often, there's more of a market in spot position spreads than in the outright.
Again, reference the "not always" portion of the above sentence.
Wishing you the best for which you can hope.