Metraman - Welcome to the forum.
Where about are in you in Michigan and where in Florida are you going?
What yr are your skis?
I suppose you could run a fresh water hose to the skis, and flush it that way. You would have to hook up the hose to the flush outlet and that's near the pump, it might be a little difficult to do in the water. Make sure you spray down the motor after each salt water use with a good protector.
PS. I wouldn't leave the skis in the water for more than a couple days.