Anyway, some of the mechanisims on these seem
cheap

You get what you pay for. I use load binders on my pontoon boat. They are like
the ones truckers use. I think I got them at Northern. They have a flat metal
"hook" that fits in the edge of the trailer "C" channel. Look at flatbed trucks
with the 1/4"x3" rail around the bed and you will see these in action.