ScottG wrote:
Cinder blocks have a habit of disintegrating without warning. I prefer wood or plastic.
THIS^^^^....But mostly, because when something goes wrong in hitching, being on big blocks can cause damage, when the legs fall off them. Also, when doing a pull test, if you do NOT extend the legs to the ground, you could drop the fiver on your truck bed. Because all you need to do is pull it forward about 8 inches and you're off the end of the block. if you have 6" of bed rail clearance, and you are propped up on a 10" block, what happens when it drops off the block? If the hitch lets go, the only thing from stopping the fiver from hitting the ground is your truck bed side rails.
So if you need to extend the legs for a pull test, it's just easier to set up with the legs down on a 2X8 anyway. If you need more stability, there are better ways to get stability.