Get the 302
Get the 302 V8 because of the low end torque and the heavier duty transmission. I think for the years that you mentioned, the V6 comes with a 5R55?? transmission, and I don't think that you can even attempt to pull in OD. The 302 comes with a 4R70W that is a pretty tough transmission. It can pull in overdrive as long as it isn't hilly, plus an electronic shift kit from B&M is less that $40, and I do use one even when I pull my <2000lb. boat and trailer combo.
On top of that, the 4R70W transmission is basically a wide ratio AODE, which is an electronic version of an AOD. Also, the 4R70W is the automatic in V8 Mustangs (even the Roushes) and in some of the F-150 trucks, although most of the ones that I have seen were 4R100s.
To let you know of my trailer pulling situation, most trailers don't drop my fuel economy more that 1 mpg in town. Since I can pull in overdrive, one trip from Jackson, MS to Atlanta, GA was about 19 mpg without more than a few tools and my clothes for a couple of nights and no trailer. I drove from Atlanta to Starkville, MS a few days later with a 5x8 Uhaul full of old furniture, that I inherited from my granparents and was sitting in storage at my aunt and uncle's basement, for my apartment. I got between 16mpg and 17mpg driving without stress due to engine power. I remember pulling a boat from Atlanta to Jackson that was similar in weight but less drag with the '94 Explorer, and I got a dismal 14 mpg and was quite restless the entire way since I didn't have enough engine power, and I was definitely driving slower as well, on purpose. I actually forgot that I was pulling the Uhaul with the Mountaineer V8.
Plus with the K&N filter and modified "cold air" airbox, I actually get better fuel economy out of my 302 than I ever dreamed of my '94 Explorer that my sister now drives. Since the mods, I've actually have gotten between 21-22mpg running the AC & passing some vehicles on the 2-lane highways, doing between 65-70. Ironically, I have the biggest engine in my family, and I have the best fuel economy.