I am going to go against the grain here (and get flamed probably) but I do not think you HAVE to put guages in to run the EZ safely. From what I have seen the EZ lowers max EGT on a STOCK truck by 200 degrees or more. I do not believe that you can create high EGT with a stock truck and just an EZ. If you do put an EZ on without guages you ABSOLUTELY MUST put the MAP connectors on and the boost elbow on. Each and every instance of even close to high EGT that I have seen with a stock truck or just an EZ/VA type box on a stocker has been at low rpm (under 1800) or high rpm (over 2700) and sustained heavy throttle. Run it in the powerband and temps are not an issue in my experience.
I do have guages and would not want to drive without them. Guages are worth every cent spent IMO. Guages should be the first addition to your truck, with fuel pressure having the highest priority, then EGT and boost having lowest priority.
I apologize if this post seems contradictory, but NEED and SHOULD are two very different things to me. I WANT guages, but do not feel that they are necessary to the safe operation of my truck.
Final disclaimer: if injectors are added the bet is off, guages are needed beyond just an EZ. Also I would add that if you are the type of guy that will plant the go pedal on the carpet and hold it there for minutes on end, you NEED guages on a stock truck too. Think about all the CTD's out there, I would bet good money that less than 3% have guages. How many have burned up?