slide-out question

I'm planning on a large slideout for my canned ham.
I've seen some people do them without any kind of track if they're smaller ones. I know very large RV's are commonly using Lippert rack & pinion style slideouts.
My current thought is basically something like:
Clearly I'd have to leave a 2" space for the walls to slide through the floor so I'd be needing to put some backing on the floor to provide strength when people are walking over it. I'm thinking what I'll do is have the slideout go significantly under the floor so when it slides out the slideout itself provides some of the stability the floor would be lacking without it.
Unfortunately, that kind of building takes extra weight that I'd honestly rather save if possible. Does anyone have suggestions for how to do a slideout like this and save weight while realizing that you'll have at least one 300 lbs guy walking on it so using thin plywood is definitely not an option. Maybe an aluminum grid put across the floor underneath plywood wouldn't require the support? (it seems to work out to about 90 lbs in weight for the extra bit of floor to provide strength)
Thanks!
I've seen some people do them without any kind of track if they're smaller ones. I know very large RV's are commonly using Lippert rack & pinion style slideouts.
My current thought is basically something like:
Clearly I'd have to leave a 2" space for the walls to slide through the floor so I'd be needing to put some backing on the floor to provide strength when people are walking over it. I'm thinking what I'll do is have the slideout go significantly under the floor so when it slides out the slideout itself provides some of the stability the floor would be lacking without it.
Unfortunately, that kind of building takes extra weight that I'd honestly rather save if possible. Does anyone have suggestions for how to do a slideout like this and save weight while realizing that you'll have at least one 300 lbs guy walking on it so using thin plywood is definitely not an option. Maybe an aluminum grid put across the floor underneath plywood wouldn't require the support? (it seems to work out to about 90 lbs in weight for the extra bit of floor to provide strength)
Thanks!