Rear Floor Separation: Rpod 180

I have a 2021 R-pod 180 that I purchased used. It looks like the rear floor has started to drop/separate from the walls. It happened before I owned it, and I need some ideas on how to fix it.

My current plan is to use a hydraulic jack to lift the floor a bit, and install a couple formed outriggers on the inside/outside of the frame to hold it in place. I'm hopping this will better support the floor if it has started sagging, but it may be an issues with the wall, or something else.

Please let me know if you know what this is and/or have a good trick to fix it.

Thanks!

Here are the pics:

Side shot: https://drive.google.com/file/d/1592_cw34oVLJTVRGUTrBtgct0-IHhZ3T/view?usp=sharing

Rear of trailer: https://drive.google.com/file/d/156xNlkEyo6pWCoAJF3N4U2YU5vp46YO5/view?usp=drive_link

Underside (shows a factory outrigger in place): https://drive.google.com/file/d/15E7kYHbzB0g9QB3sTZ0PPfSKu7-wPqx6/view?usp=sharing