I know people with dual cases in their 4runners with no cv on the rear and there wasnt any complaints.  My boss told me i would want a cv on the rear after i went duals so thats what i did.  I made them, slapped them in and havent thought about them since.

Pick up an ifs front cv, probably the easiest to get ahold of in my opinion, get it clearanced and you should be good to go!