Reply by Eric

Lots of good ideas here. So I will add another point to think about.

Fir additional vertical strength add a style against the legs between the top and bottom rail, then add a short block below the bottom rail to the floor.

Also add a joist from the front rail the the back rail placind against the legs. Then a few in the middle section.

As for the top 3/4” plywood will work well. I would band the edge of the plywoodakimg it higher to acomindate either MDF or hardboard. (For a replacement top) drill a 1” hole in the center front edge of the plywood, this allows you to push the MDF up and flip or replace.

Good luck on your project.

-- Eric, Upstate South Carolina