If you are worried about it, why not just make the vertical supports out of 2x4's? I have a stand made out of doubled up 2x4s that could probably hold up an SUV without much worry.
In the link you posted, he uses 1.5" ply. In your case you may have trouble with the 3/4" ply and the screws bulging the wood when you go to fasten it together, particularly the top being joined to the verticals, since you have less wood thickness. That's really the only thing I could see being a problem.