Use Truck to test towed setup

You can do it, but if you don't have a braking system installed (or even if you do) be very careful. I used to have a 2002 Ford Focus (lighter than your Jeep) and a few times I pulled it with my Chevy 2500HD. Even though the Focus weighed less than the Chevy's payload capacity, once or twice the slight upward angle of the tow bar combined with the Chevy's already light rear end to make stopping in the rain dicey.

I probably wouldn't do it just to test the towing setup. The only times I pulled a toad with my pickup was to bring a car in for service by myself and drop it off.