If the only place you are going to get stuck is on level ground, and not because you are in mud, then 6000lbs will be fine. However, if you are actually going to wheel, and want to be able to unstuck yourself...... or someone else, you will need at least an 8000lb. I have winched an 83 Toyota standard cab, which weighs well over 1000 lbs less than an Explorer with my 8000i. He was in heavy mud, and even with a snatch block, we barely got him out.
I also had a friend with a Fourrunner (84), that was told a 6000 was plenty. He probably still regrets it to this day. Again, the FourRunner is alot lighter than the Explorer.
Frankly, the difference in price between a 6000, and a 9000 is not much. This is especially true when you are stuck between large rocks, and just want to get home for dinner.
If I hadn't have had this 8000i for 15 years, I would have put a 9000 on my Beast.
Gloria
93 EB Explorer (highly modified)
94 F150 Lightning