Its been done in a 6 Here is the link. You'll also have to figure out W&B issues with the moment of heavy ski's way out there in the tail. I was amazed at how heavy my new pair of skis are when I put them on the scale. I asked Dan C the same question a year or so ago, and we figured with the right engine (200 hp) and CS prop up front the W&B was doable using his W&B calculator.
 
I've seen guys remove the rear seats and bulkead and load camping stuff from just aft of the rear stick all the way back. Keeps some of the weight forward. Would work if you didn't have a passanger. I put a tube in my -8A, but it is for lighter stuff like fly rods or an airshow umbrella!