If all you want to do is move around a trailer, you should probably look at a used tractor or maybe find some old airport towing tractors. I have seen them as cheap as $500 on eBay before. They have the pintle in the front to allow greater maneuverability.

 

I think you would be Ok with a big bore. I'd make sure it was a solid axle model though. I am not sure an IRS machine would handle it without damage. If you look through my picture albums, you will see a large trailer that is 11 ft tall and weighs empty around 4500 pounds. I do much the same with my Honda Rubicon all the time. Just for manuvering. You can also find what they refer to as a trailer 'Mule" that is built for this. Not very fast, but will move anything. Not overly expensive. Probably much cheaper than replacing or repairing a quad these days.