It's not so much about the number of cylinders as it is about the weight handling. Although, most tow vehicles that can handle a travel trailer do have 8 cylinders.
What is CVWR when referencing a trailer? The trailer will have an empty weight, a GVWR, and will actually weigh somewhere in between. If that 3750 is a brochure weight, add 1000 lbs. when considering a tow vehicle. If you are thinking of a tow vehicle at the lower end of towing capacity, the vehicle's PAYLOAD rating will rule all. It is on a sticker located on the driver's side door jamb.
The payload should not be exceeded by weight of passengers, cargo, hitch weight, and the tongue weight of the trailer.