Goto
www.ford.com then to brochures, Ranger and towing specs. A 2-whl drive Ranger should tow a 2720 OK, as long as you get the automatic transmission.
Neither a Ranger nor an F150 with a manual transmission will do the job. Ford light duty manual trans are not up to the task.
BTW, our fully optioned 2720SL, packed, fresh water and water heater full and gray tank empty weighed in at 3340lb on the axle plus about 490lb tongue weight - and we don't pack that heavy. My rig was weighed on a certified truck scale.
So if you figure 4000lb. you should still be OK with a good margin with a 4.0L Ranger 4x2 with tow package - it appears to be rated to tow about 5800lb.
Hope this helps.