I have one of the Northern sprayers and it has been absolutely awesome. The pump is high quality and the tank is roto-molded HDPE you could probably jack you tractor up on. The spray bar is plastic but the wand sprayer is metal and I always wash everything out well with detergent when done. Used it a half dozen times over the last two years on my L3800, with the tank in the loader and the hand sprayer hose run back to the cab. I was planning to build up a spray rack using one of those 2' hitch racks mounted to a 3pt frame with a 2" receiver hitch.
I tried it in my Polaris Ranger and its actually easier to spray from there. Don't have to worry about running the loader through a fence.
If you do spray around fences, raise your loader way up and out of the way.
Great tank though. I think it was the large ATV tank... 20 gal or so. Has the bungee bulges on the sides to strap it onto a rack. Pump runs at 70psi, tops off pressure and then stops until pressure drops.
Ray