I fly several pusher planes.

As noted the engine will get hot even in flight, because it lacks the cooling action of the prop's airflow, even when using a smaller prop that does not load the engine down as much as a standard prop.

I find that I have to richen the high end a good bit, enough to force a marked reduction in available power, to keep the engine in it's operating range and prevent my engines from seizing.

I learned this the hard way with one pusher...

After reading one of Downunder's posts about head temps I purchased a laser temp meter... with that I could find the optimal tradeoff between richness and temperature rise.

I adjust the HS needle to keep the engine head operating well below 360 degrees ( at the hottest point I can measure ) on the ground at full throttle.

That worked great and resolved my pusher engine overheat problems.