Odd rig...

Yes, I'm aware of the polacre-xebec rig used on the Pelican Of London - based my sketch off of that.
As PAR said, the fore & aft masts would act as springs, but won't the stays keep those masts straight still? Since masts stay away from those triangle sails it would mean, although they add a little of drag, but sails aren't affected by masts which would make a better wind flow. Both triangle sails can be rolled in to those horizontal booms. Sails' pivot axis is vertical.