I made a set like that awhile back except I just used a piece of 3/8" all-thread instead of the pipe clamp. I secured one end of the all-thread to the bottom block by welding it to a piece of strapping and lag bolted the strap to the block to keep it from spinning when tightening the upper nut. I use a ratchet wrench to tighten it up and it will drag the wheels if I forget to take it off before driving away. I boondock mostly and have to raise one side plenty sometimes to level my trailer and this keeps it from rolling off the blocks. Works lots better than the store brands.
26' 1999 Forest River Sierra TT behind a 1999 Ford F250SD PSD