Maybe if you took a large beach towel and rolled into a cigar shape and put that between the window frame and the brackets that would help prevent any warping. I hang my soft windows from wood clamps and I cut up a towel and put it between each clamp and soft window just to prevent any marks or indents. Just being safe.

 

I had a similar thought, but with the idea of putting in a little shelf along the bottom to take some of the weight off.

 

A little extra padding couldn't hurt, but those brackets come with foam padding on the bars already.

 

I would be really really surprised if hanging the doors like this causes damage. I have the same exact hooks that I have been using for months to hang my doors. My doors are off about 75% of the time, so they have collectively been hanging for a total of about 3 months. I have had them hanging for as long as 3 weeks straight. I have not had any problems with it. The door surrounds look and feel quite sturdy. The rubber seals where the window seals against get a little bent after leaving them hanging for a while, but after a few hours they are back to normal. The actual door frame still feels just as strong and the door still lines up just the same. I would be more worried about not hanging them personally, because if they were just against a wall or something where they could get dropped or scratched.

 

how about doing the exact opposite and having the brackets mounted close to the ground setting the doors on them. Not sure if there is enough room from the pictures of the brackets above or not. The tops could be tied/bungied to keep from falling over. Just a thought if the possibliity of warping is a concern.