A company called Trailer Valet has just released a series of remote-controlled robots that can tow up to 9,000 pounds. They call them the RVR3, RVR5, and RVR9. Although they don't say what RVR stands for, the number apparently denotes its weight class.
The RVR3 sells for $2,100 and can bear up to 3,500 pounds. The RVR5 can move 5,000 pounds and retails for $3,400. The RVR9 is the brute of the bunch capable of towing 4.5 tons (9,000 lbs). That one will set you back $4,100.
The device moves on two independently controlled treads like a tank, so pivoting a trailer is a breeze. They are relatively small measuring only 22x18x12 inches but are also sturdy weighing between 45-77 pounds.
The RVR5 and RVR9 are available now from the Trailer Valet website. A release date has not been set for the RVR3, but pre-orders have started.