I just purchased a 2004 dodge dakota.?

I just purchased a 04 Dakota with, are you ready for this... 13,788 original miles on it. No thats not a typo. This truck was actuallly driven by a little old man and his wife on nice days to take their bicycles down to the park to ride. Anyway, I was wondering what the running temp. should be. Also, does it hurt anything to run an engine cooler by changing the thermostat. I am considering taking a road trip out west and I don't want it to over heat if I drive through the mountains or deserts. Any help.