reefer floor delaminated - how to fix?

So this is for a stationary reefer 40ft hc container. I apologize for posting here but when you google reefer floor repairs, bouncy, etc this forum is what mostly comes up. It's such a niche thing there isn't much information available to someone who's not really in this type of industry. Hoping someone here can help.

So not hauling but using the reefer as a fish hatchery - there will be a lot of weight in it. I've spent the last year getting electrical water, and everything getting ready for use. There was a bouncy spot in the floor but it's spread to quite a bit of the container and I believe this means it's delaminated. There are no obvious cracks or other damage just the floor dips and bounces when you walk around in much of the container.

I just want whatever will be stable and ideally the cheapest. I bought the container because it was considerably cheaper than any other kind of building. Looking for something that will last years but necessarily forever.

The one suggestion I have been able to find is to drill in long self tapping screws, unfortunately I haven't been able to track down any 6" self taping metal screws. I'm in Canada so I'll have to order them from the US it looks like.. I'm going to try this first but if this doesn't work any ideas?

The ideas I have are as follows :
Either have steel plates welded or drilled onto the existing aluminum, I suppose 3/4 plywood could work too. Fill with concrete to level the floor.

I am open to any ideas but would prefer not to have to remove existing floor unless absolutely necessary as there is already a lot of stuff in the container. Again apologize for posting this here, if you have any suggestions where else I could seek advice I will check them out. The only other thing I could think of would be container home modification people but they seem to be mostly dreamers with no real knowledge and unlike a home to use the container as a hatchery only required electrical and plumbing, not serious modifications to the actual container (I had a man door added that's it).

 

I'll have to figure out how high I can lift it without disconnecting the power and water lines. It is in a permanent spot. Container sits on a professionally leveled gravel pad (was like 6 truckloads of gravel) and then lifted up in the corners slightly with heavy duty concrete pavers, so it's just a couple of inches off the ground. I got the container last December and after the first freeze / thaw it stayed level so I figured it would be good to go.

Seems like this is a much bigger problem then I initially thought...