6 inches is a good distance. The further you get away from the port the cooler the temperatures.
The AFR sensor won't last long enough to get a reading.
Running a two stroke wide open is an easier tuning challenge then a roadracing setup.
The easy way is to lean it out until it melts then back off a little.
All sensors are relatively slow to react. You can melt it before the reading stabilizes.
1100 on EGT is as much as you want to run. You are approaching the melting point of the piston past that.
I also run a head temperature sensor. The EGT shows rapid changes. The head temperature shows a more stable reading.
At some point the EGT will hit maximum and then drop as you continue to lean it out. If you end up (rare) in that condition you will melt it before you figure it out.
Plug readings and piston inspection are mandatory. The piston and head have to be spotless. Any carbon creates a hot spot. At the end of the run kill the engine. If you run it back to the pits the plug reading is worthless.