Building a platform

I've currently got a fairly standard platform setup with the plywood layer on the floor, on top of which are my horse stall mats. There's a leak in the shed from either the floor or roof such that when it rains hard (frequently enough in louisiana), water gets into parts of the shed for a couple days, namely around the platform. Maybe I can find and fix it,, maybe not. Besides deteriorating the wood over time, there's also obvious concern about mold developing.

Thoughts: I'll do one of two things. One: just do two layers of horse stall mats. But would it be too squishy under foot? Not trying to break my concrete, which I'm paranoid about, and I squat and pull close to 500 and clean two plates occasionally, for reference of the beating I give the floor (I have two sets of bumpers). I already am worried about breaking the floor over time (it's about a 15'x18' shed). I'm sure it's fine, but peace of mind is worth something.

Two: basically the exact same thing except I'll put a nice wooden layer in the middle of the platform on the top, where the rack is and where I'll be pulling. I figure that will add some stabilization for my feet but I'll still have a waterproof bottom layer and double the soft mats for dropping the plates.

Any thoughts or experience on either end?

Edit: I like the idea of the wood strip, but I'd consider just two layers of mats because one it's easier, quicker, and cheaper to do, and two I sumo pull (narrow, but nonetheless) and I don't want to pull a small carpet out each time I pull to keep my feet from slipping.