Which truck are you talking about? If your talking about the GMC, then I can't answer for plowing yet because we havn't had any snow yet. It should plow great other than the fact that the turning radius is on the long side. It tows great, the duramax (all diesels would) has tons of power. It hauls very well too; don't feel like the things going to fall apart when the beds overloaded a little. If you meant the chevy, then it too is a great truck. Plowing-wise, it is perfect. It could use a little more power for towing, but it's not too bad. EZdumper makes hauling materials a breeze. We abuse the thing when it comes to hauling. We constantly haul 5 cy of mulch, 2 tons of gravel occasionally, all in addition to the weight of the dump. Let me know if you any other questions about the trucks.
Our trailer is a 6x12. It was fine at first, but it is on the small side now. We are able to cram a 60" ztr, 36" wb, and 21" on it. A 16' would work a heck of a lot better though. We went with the 12' so it would fit in the garage (no unloading at the end of the day). We will probably step up if we get a shop or something someday. I would go 16' if I was you.