Ive not heard of anything like this before but I dont know of one guy thats swaps the boom on his rogator for a applicator bar. He sprays his crops and sidedress corn with the same unit. Have never seen it but if it works on the rogator you should be able to fit it to a pull type as well. Could be wrong but I think he built the bar himself though.
You should look at the Bluejet line. I have a landtracker caddy that I have my corn planter on and I can put my drill on it also. They are well built. I have often thought that you could make a pull type sprayer and pull type sidedress rig out of one. I have attached a link to the caddy. They have other stuff too. Good luck.
I've thought that it wouldn't be very hard to build one, just use a big 3pt hitch on the back of the sprayer with a quick hitch to mount the boom to so you could unhook it and pick up the side dress bar.