Man, our trailers are so much a like just a few differences, mine even has an extra plate hitch on the back too which I use for tie down point. I too want to make side slide in for my ramps, can't wait to see yours. Mine has a single steel rail right down the middle though, would have to work around that for ramp tray.
I have hauled a few cars on mine, actually drove 4 hrs to Evansville Ind. to pickup a 4200# Astro van for a buddy, trailer handled it fine.
I got ahold of a spare tire winch off he back of a wrecked 97 Chevy pickup truck, going to mount it up under front of trailer in the hitch rails "v" so it's out of the way and up under trailer out of weather. I'm also going to move my light brackets up to upper rail as I tear them up on everything it seems cause they are mounted low.