Rob,
At that temp you are below the temperature range of the medium fronts, sifts should be much better.
Raise ballstud towards horn, lower absurd towards chassis.
Regarding Ackerman my servo horn just shy of 2mm clear of the upper arms. I'm guessing my servo is 2-3mm further forward than hara's but without knowing the servo horn lenghth there is no reality comparison.
Out here we have gotten or f1s about 1/3 the way between 17.5 & 21.5 sedans outdoors. On some of our carpet tracks the 17.5 cars are only a few tenths up on f1.