Cargo Securement

Its a beautiful thing when flatbedders work together rather than argue lol

 

I second the firehose. I have wrapped pto/hydraulic lines in it. Battery cables. Even chains to chain down some high end stuff. It will outlast what ever you put in it.

 

I use that black and orange load rated plastic rope. Cinch her real good, and it hasn't failed me yet. Our dunnage racks are very similar to the pics. Cheap, quick, and easy.

 

If you were near me, which you may be, I'd cut off a few feet of fire hose for you or check with your fire dept. They may have one they can't use anymore. They will probably cut the end off first so it won't be a liability issue if someone tries using it for fire fighting.
If you have an old piece of tarp cut it the length of your tray plus about 4 feet extra. Then cut it the depth of your tray times 2 plus the height times 3 or 4.
Empty your tray out. Lay the old piece in it so that its centered with the extra hanging over even on each end and the other way so that when you put your supplies back in you can pull the ends over it and then wrap it the other way.
This serves two advantages, It keeps your supplies out of site plus it keeps road grime, water,salt,snow etc off it so its a lot nicer to work with.