I have been using the Tri Levelers for more than 10 years and found that the steps are sufficient to sit level and stable on.
As noted when on the leveler just putting the RV in park and setting the parking brake at the same time will keep it from moving,in all these years I have never had a problem with any movement.
I had a set of wood ones I made up for my previous RV, as pictured above,I found that they were VERY heavy about 24 Lbs each, and hard to stow taking up way to much room.That is why I went the way I did with the Tri Levelers,light weight,easy to stow and I have yet to find a spot that needed any thing larger.