Though the Rav4 is only rated to tow 1500 lbs and the UHaul 4x8 is 850 lbs empty, leaving just 650 lbs of stuff you can cram in it.
My brother hauled a 4x6 trailer with 3 passengers and all their college supplies cross country to BYU with a Ford Escort, which was half the size and less than half the horsepower of the Rav4. It can be done.
Biggest thing is remembering to downshift when going down long, mountain downhills. The brakes aren't built to do it by themselves and will turn red hot almost instantly if they don't get help.