prepping canvas for shipping from dry to humid environment

[mstevensphoto]

Hey all,
   I've sold a set of 14x14's and a 24x24 canvas to a client who moved from very dry CO where I am to very not dry New Orleans. I've got the canvases ready to go and am fighting with ideas on how to best stretch these to ensure no warping or sagging when they get to the humid environment. I'm planning to mount the 24x24 to gator and can't decide on the little ones. Typically I use the IG wrappe system. Thoughts on preventing sagging going from dry to humid climate?
thanks
Mark

[shadowblade]

Stretch them on spring-loaded stretcher bars - that way, they'll adjust their size based on expansion and contraction of the canvas and always stay taut.