Do you plan on running independent fans per HX? If your constantly moving no issue but if you see any stop and go traffic the IAT heats up quickly.
FWIW my core size is 22" wide x 9" high x 3" deep and i have no IAT issues mounted on the lower half of the radiator opening
Also if you can calculate the needed BTU/hr Setrab has a pretty good data base.
http://www.setrabusa.com/products/oi...ine/index.html