Not sure how your set up compares to ours but for underbelly storage - we use well-labeled covered totes, so you can slide them out & stack them on the ground (even in the rain) until you get the one you need (Sewer, Fire stuff, tools, awning stuff (lights, etc.)). Find a size that will fit easily thru the opening.
We have the anti-gravity chairs, too. Store them on the dinette (made into the "bed" when we travel) lying flat with the "bottom" of the chair away from the wall, so if there's any dirt on the 'feet', it won't hurt the wall.
Congrats on your camper. Welcome to the forum. I read these posts every day - it's the only thing that keeps me sane until spring.