Go with an inch then, you don't want it too tight, just enought to stop the squeek. while you have it off, check all the pullies for smooth running with no "Grinding" thinks like the Alt may be a little stiffer, but smooth. obviously the main drive pully won't shift!
Dunno if the water pump is belt driven on the Jeep, but if it is, that's the one to be sure of as if that's very stiff, you tighten the belt so much to stop the squeek that you take the bearings out on it, the Alt or other pullies.
EE