The difference in power between the 5.2 and the 5.9 is 25 HP and 30 ft/lb torque. Both engines are thirsty and anemic by todays standards, but I don't think you will feel much if any difference if you were able to find the bigger van with the bigger motor.
For the record, I had a 1994 Dakota with the 5.2 (as well as some Grand Cherokees) as well as a 1996 Ram 1500 with the 5.9, and used them to tow a 4500ish pound boat. Couldn't really tell a difference between the two engines from what I remember.