You are not going to find a GCVR on the trucks data plate. Your truck should be able to trailer that telehandler without a problem on a suitable tag trailer. I'm not sure what your empty weight on that truck is, but I'm going to guess it is around 15k give or take. Lets say 11K for a 20ton tag, and 26k for your handler. That puts you in at only 54k gross. As long as you keep your axle weights legal you should be fine. I have personally run 3208 equipped trucks, with 5-speed Allisons :confused2: at 65-70k. You are not going to win races, but the 3208 will get you and your load there.
Laws vary state to state, but if you can legally qualify for the farmer CDL exemption it should not make a difference if you are pulling a trailer or not.
Tag trailers are cheap these days, when I was looking for my 14k deckover I found lots of used 10-20 ton tag trailers for half of what the 14k trailers were.