They are going to be handling heavy water pipe, and might need to hook a chain on and pull stumps, so I built this one out of 1/4" wall tubing and 3/8" vise plate. The mount weighs about 25#, and the vise another 70ish so it's a heavy chunk.
I can build them out of 3/16" tube and 1/4" plate instead, to save a few pounds, and a smaller vise would serve paddock use just fine. I can also add features, like a locking wedge so it doesn't rock in the receiver, or a step, or...
I just ordered a can of cold galvanise aerosol, if that works out I'll paint them.
They will be built to order so I can customize the design, features, and dimensions. The one pictured cost the water co $240 without the vise. Thinner wall tube, or a flurry of orders, could bring the cost below $200 for the mount only, without the vise.
Definitely buy your vise locally, shipping would be expensive.
I would need a tracing of the vise baseplate, and some measurements from your truck. I'd supply the mount and attachment hardware.