a couple or one longer piece of angle could stop it slipping. I used bolts as well as two small holes are hardly noticeable & dont really need nuts as is just a locating thing & preventing the slippage.

I saw my B.in Law in trouble once when one of his ramps slipped while loading a tractor from a trailer to a truck. Stupidly I ran over, (while his staff were watching and awaiting the inevitable) and held the slipped ramp under the rear wheel while he gingerly reversed. I had the leverage with the ramp and those little B1750 Kubota tractors have great 4wd & the front wheel wasn't needed. He was in shock as well as embarassed : only his pride was hurt, but I was ready to drop & gallop if my instantaneous stupidid reaction failed=I'm no death wish hero nor B. Willis!LOL now. My eldest daughter says "if you were a cat you would have used all of your 9 lives.