We're not actually having any problems with fouling. I'm just looking for
new techniques to keep it that way.

I've heard that the desirability of keeping ground RPM and temperature up
has more to do with lead build up on the exhaust valve stems than plug
fouling but I don't know how good that info is. I would think that a very
lean mixture would benefit the valve stems as well.

Probably no good or compelling reason to run the engine this way but it's
interesting to find out that it can be done.

This engine has very good mixture distribution and I've been experimenting
with running it slightly lean of peak in cruise. Since we only have a
single cylinder EGT and CHT set up, I restrict that operation to 60% power
as I don't know for sure where the other cylinders are operating. It's a
little rough if you listen for it but CHT goes down a bit. This worked very
well just after the engine was overhauled and it then got rougher. Now,
it's getting better. The variable is probably very mild plug fouling.
Staying lean and clean, even below what is required for smooth run ups, may
pay off in this regard.

--
Roger Long