Thanks again for the input all: I copied the "Block Idea":
I crafted a block (painted yellow), bolted it to the center floor board and strapped the PHD down as pictured above. Ran into some roadwork and had to stop and wait for an escort; so I got out and snapped this pic at sundown. The Kioti CK30 HST was rock-solid tied down this way the entire 450 mile round trip from Tonopah to Carson City, NV.. probably overkill with 3/8 chains and the wide straps..but it didn't budge a bit. BTW- That is an Iron panther 7 X 18 Trailer.
