what is on the end of the buildings?  Is there enough "wiggle room on the slats?  Could the ends of the building be open enough to take a tractor and "pull" the slats out of the end of the troughs?   (like a rack in the kitchen oven)   pull them out clean em off and push them back in.

 Plan 2..  skip the skid loader, low trailer with hydraulic arm that would reach from one side to the other and lift out the slats and place on trailer.  the trailer would be self powered hyd drive motors with ground controls.  Hydraulics would also run the hydraulic arm. Walk along behind powered trailer reach from side to side pickup slats place on trailer doesn't take much of an arm to lift 2-300 pounds..  Arm would need  to go up/down swing 240 degrees and in/out.  2 guys could pull up a "slat" and place on trailer in 1-2 minutes.

If you wanted less work,, put a pincer on the end of the boom, set down between slats, pinch, and lift out the slat.

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