Afe bladerunner & air intake
 

Would just adding these air supply & delivery improvements to a stock 2004.5 dodge diesel require adding any guages (already have a transmission temp guage). Also, would these additions actually give any better performance/ fuel economy while towing a 5th wheel or would it just cost additional money with little noticeable change in performance and/or fuel milage?

With more air you will get some better mileage, and a little better performance. But nothing real dramatic. Gauges are always recommended because it gives you a first glance at a possible problem. But, when you add air improvements your are not going to increase EGT's so you don't need gauges because of these improvements. It's when you start adding fuel when you need to play close attention to temperatures.