From reading your post, it sounds like to me you know something about how fuel is dispersed in the engine. This is only a guess but talking about lean of peak operations require such knowledge. As you know with lean of peak operations, they have a CHT on each cylinder as well as an EGT for each cylinder. They also have GAMI injectors that precisely meter the fuel and air reaching each cylinder. A setup like this is not cheap.

Since you are concerned about cost (and I would too as you wouldn't necessarily get out what you spent for GAMI injectors) this is what I would do. I would first install a CHT for the hottest cylinder and a CHT for the coolest cylinder. This would give you a good ballpark on what the engine is doing. This does not allow you to diagnose quickly if a cylinder is going bad though.

Later on I would install a single EGT knowing it is an average of all the cylinders. Lean of peak operations that I have read give a very strong argument for staying away from danger zone or the range every pilot was initially taught to lean the airplane at altitude above 3000'. Thus, to me, the only value of an EGT is to ensure I stay more than 150 degrees richer / cooler than peak EGT.

As a side note to others reading this, I would not under any circumstances run lean of peak without the required equipment. Doing so will quickly damage your engine beyond repair.