I got a 14', and its going to be a tight fit. I chose the traditional manual legs so i could set it up 'carport' style. We have a side room that we LOVE and it works best with the legs to the ground.
Odd your Fiamma was so hard to put up. Mine is easy to set up, one person can do it with ease. Once I got the ceiling braces, it was almost usable! Before that, it would flop around in any breeze.
I removed the Fiamma awning by first (sorry...) opening it up all the way. Then you will see screws going into the coach on the backside of the Fiamma housing. Mine had 3 on either end, and a couple in the middle.
Once the screws are out, retract the awning. The box may pull away from tha camper a bit as you wind in. Get it rolled up as much as you can. I removed mine to replace the awning fabric, and the torn fabric made it so I could not roll it up all the way. I wrapped a few bungee cords around things to keep it together on the way off.
Once retracted, Have one person lift it on either end, and it will lift/rotate up towards the roof. As you approach vertical and beyond, be ready for the awning rail (on the camper) to release the part of the awning housing that is retained. Once the awning is free, both parties can go down their ladders holding it.
On mine, we did not know that the awning released if you rotate it far enough, and we slipped it out towards the back.

Real PITA and quite the balancing act at the end. Once I knew how it locked in, reinstalling it was easy.

Hoping to remove it one more time to install the 14 footer.
Hope that helps!