I think I'd be more concerned with winter winds and low temperatures in your climate. While tough varieties like Nova Zembla are often listed as ok for full sun situations, such locations are usually far too exposed to winter sun and wind. Artificial barriers such as burlap or snow fencing may be one winter solution if you don't mind the look of such things, but full summer afternoon sun when the temperature is in the 80's or 90's is not going to make any rhododendron happy. Nebraska would seem to be a very challenging climate for rhodos, so I'd check with the place you bought them or your County Extension Service for advice.

generally, partial shade in hot regions, but will survive when watered every morning (until they are well established) in well draining soil. mulching will help.

they will survive light freezes. best to cover them up for the first few winters during freezing temps.

They'd better survive more than "light freezes" in Z5! At 20 below zero the freezes are not light!