Using your exhaust temps as a guage for tuning may work, but there are big problems getting a good accurate measurement.
Problem #1. It is impossible to get a good reliable connection between any thermocouple type temp probe and the pipes. Too much surrounding air interferring to even get a halfway accurate reading.
Problem #2. Although a infrared thermometer sounds like a great option there are problems here too. You need a good quality thermometer, many of the low end only measure temp over about a 6" area, these are like the 8 to 1 distance to sight models. You need about a 50-1 model or at the least a 25-1 made for smaller measurements. Lastly you cannot measure infrared temp on chrome. The chome acts like a mirror and all you will measure is the outside ambient temp. This can be worked around by adding masking tape to your pipes and reading the temp on the tape, but the "very" last problem here is normal masking tape will melt to your pipes in about 3 seconds. 3M makes great high temp masking tape, I think it's #213. You can only buy it in a case and it's about $18 a roll. Not going to get it at Walmart I'm afraid.
