I have a rather extreme idea Lynn...
Be the embodiment of the worst stereotypes of a male you can be for her during the summer in terms of appearance.
Meaning, except on the days where you are allowed to let out your inner girl, do not shave, rarely bathe, be more slobbish, etc. (Heck, except on the days where you are allowed to shave, grow a full beard not just a moustache and sideburns!) If she asks about any of this or wonders why you are less clean and neat and all that, you need only say that those represent parts of your feminine side and you are going along with what your wife wants in suppressing that because you love her. Then see if she does not want to "reopen negotiations" before August!