Like Wes said, I run a 7155 over the road every week, Somewhere over 80,000 mi since July 2016. Haven't had any problems with the air system. I started out with a 2009 Fort Polk overhauled tranny, I did pull the rebuilt valve body off and put on a brand new one out of the crate. I do use a Parker regulator set at 95 psi as R R Racing suggested, seems to not slam the shift forks so hard. And I use a Bendix AD-9 air dryer, I never have water in the air tanks. Down to 0 degrees, no air problems and no valve body heater either.
I would say the most important thing would be dry air. Get a good dryer and don't use the alcohol bottle. If it sits a lot, the oil mister might not be a bad idea.
If I remember right, the air dryer was added to the M916 I drove at Fort Carson in 1987, I don't think the trucks came out with them new. And the valve body heater was an after thought too, I think. Probably good dry air would have solved the problems they were chasing?
Anyway, I'm going to put a heat exchanger to heat the oil in mine for another issue, torque. It's rated for 1340 and I'm putting 1650 in it with a Series 60 Detroit 470 hp and the rear clutch will slip when the temp gets down in the teens at peak torque in the top 2 gears. Not sure if it's just this transmission or if another one I have will do the same thing, haven't tried it yet. Already raised the rear clutch pressure by about 30 psi which helped.
Maybe this needs to be somewhere else, don't want to highjack Artisan's thread!