Some very interesting speculations in this thread. Please let me share with you my personal experience.
In 2012 I purchased a 2013 Hyperlite 27 with the full intent of using the rear door for a patio deck, even though this was not an optional accessory at the time. I inquired through the dealer about this possibility and was given similar evasive answers as expressed in this thread to my questions. I opted to design a ground support system instead of the cables that you see on other models.
In May of 2013, my rear door started to show signs of internal moisture from sitting in the horizontal position during a very wet weekend. I contacted my dealer and after sending several pictures, the door was replaced under warranty. It obviously had some sealing issues around the outside frame which allowed the moisture to penetrate when sitting in a horizontal position.
When I was at the dealer, getting my new door installed, by chance a factory rep was there for another situation. He was very nice to me and because I have an engineering background and knew some of the right questions to ask him, he invited me into an office where he opened up some engineering drawings of the the two different types of doors. 1) Standard door 2) Patio deck door. There were distinct INTERNAL differences between the two but most notably was an internal aluminum "U" channel spanning across the door from left to right located at the cable anchor point positions on the door. Structurally, this would prevent the weight of things placed on the deck from bowing the door when sitting in a horizontal position.
He expressed to me that I should not use a cable support system because my door was not designed for it structurally. I showed him a picture of my setup and he assured me that I should not have an issue with my ground support system.
Since then, I have used this method of supporting the door for a deck all the time with out problem.
For those of you who want to see documentation, I have none. The rep gave me nothing in writing and I was only allowed to see the electronic drawings on his computer, but after seeing the documents, I would not use a cable support system on a door not designed for the patio deck.
2013 XLR 27HFS
2009 Chevy Silveraldo 2500